Kwamalasamutu is very isolated. It is only accessible by plane or a week-plus journey upriver by boat. I opted for the plane.

After nearly a week of attending meetings in overly air-conditioned conference rooms, I was excited about getting into the field. The morning I was due to depart, however, I got a cryptic, but ominous message: the airplane couldn’t go to the interior due to flooding.

I probably should have taken that as a sign. Not that I’m superstitious, but there had been a number of bad omens up to that moment in Suriname: the four-hour passport control line in Trinidad that nearly caused me to miss my flight, the can of paint that exploded all over my bag and leaked inside, and the mysterious, yet savage mosquito attacks in my hotel room.

I didn’t think much of it at the time. While the weather was pretty good in Paramaribo, the capital, it was certainly possible that there was heavy rain deep in the forest. The next two mornings it was the same: bad weather and flooding would prevent us from flying.

The following day, I got seemingly good news: the weather had cleared enough that we could fly. The two-day delay had eaten into the several days I had allocated for this leg of the trip, which was the last before I went back to the U.S. At this point I would only have five days in Kwamalasamutu. That seemed like enough time to visit the project site and spend some time in the forest.

The flight to Kwamalasamutu confirmed that Suriname is indeed mostly forest. Outside the coastal zone around Paramaribo the only signs of humans were occasional villages along rivers and some gold mining areas. I could also see that there was some flooding; huts in several villages were virtual islands.

Kwamalasamutu is a substantial settlement for such a remote area. Up to 1,400 people live there, although there are rarely more than 400 residents at any given time due to the transient nature of its tribal inhabitants, who spend much of their time in the forest or other settlements.

Much of the Amazon rainforest remains occupied by tribal groups. While few of these live as conjured in the imagination, the state of the forests in their territories is a testament to their approach to managing the land. But like the Amazon itself, these groups face new pressures from the outside world. For the indigenous communities, the lure of urban culture is strong: cities seem to offer the promise of affluence and the conveniences of an easy life. But in leaving their forest homes, indigenous peoples are usually met with a stark reality: the skills that serve them so well in the forest don’t translate well to an urban setting. The odds are stacked against them; they arrive near the bottom of the social ladder, often not proficient in the language and customs of city dwellers. The lucky ones may find work in factories or as day laborers and security guards, but many eventually return to the countryside. Some reintegrate into their villages, others return in a completely different capacity than when they departed. They may join the ranks of miners and loggers who trespass on indigenous lands, ferreting out deals that pit members of the same tribe against each other in order to exploit the resources they steward. As tribes are fragmented, and forests fall, indigenous culture — and the profound knowledge contained within — is lost. The world is left a poorer place, culturally and biologically.

But there is new hope, embodied by efforts to enable tribes to become more self-reliant through the use of state-of-the-art technology that builds on and leverages their traditional knowledge. These tools can help them better defend their lands and offer the potential for the next generation of Surui, Trio or Ikpeng to have a future of their determination rather than one dictated to them by a society that values the resources locked in their territories over their forest knowledge and rich cultural history. Through such technology, tribes may be able to avoid a fate in which they become destroyers, rather than protectors, of the basis of their culture: their forest home.

My friend, Mark Plotkin, is at the forefront of this effort. His organization, the Amazon Conservation Team (ACT), a Virginia-based group with field offices in Brazil, Suriname and Colombia, has pioneered geographic information system (GIS) training for indigenous groups in the Amazon to enable them to map their land, not only as a means to demarcate it and win title, but to catalog their cultural links to the land. In building these “cultural maps,” tribes construct maps of their territory that go beyond the topography of the terrain, capturing the underlying richness of generations of human experience, including their interaction with the land and other tribes, and the distribution of plants and animals of nutritional, medicinal and spiritual significance. In other words, in as much as indigenous culture is a product of the land, the maps capture the essence of these tribes.

But creating a cultural map is no easy task. It can take years of work by the tribe, laying out what the map will contain, determining which communities will participate, and coordinating who in the community will do the actual footwork. Other considerations also come into play, including harvesting cycles and seasons (mapping can’t interfere with the ongoing the activities that sustain the tribe) and the treatment of intellectual property contained in the maps, since these can be used for nefarious purposes in the wrong hands, including exploitation of timber, game and medicinal plants.

The training itself can also be complex. Indigenous mappers must learn the ins and outs of handheld GPS units, GIS systems, computers, and internet tools like Google Earth before they can construct maps and monitor their territories for threats and encroachment. But the payoff can be well worth the effort: 20 groups in the Brazilian Amazon have created culture and land use maps of their territories. The maps include 7,500 indigenous names, 120 villages and thousands of areas of cultural and historical significance. In Suriname, the maps are being used to help indigenous groups get government recognition of, and eventually title to, their lands. Some of the indigenous mappers have gone on to become certified as park guards, enabling them to earn an income while working to safeguard their lands.

Plotkin was unable to join me on this trip, but Melvin and Rachelle from ACT-Suriname accompanied me. Over the next few days, I saw ACT’s mapping and indigenous park guard work in action. I also witnessed ACT’s Shamans and Apprentices program, named after Plotkin’s best-selling book about his early years with the tribe. The program passes the shaman’s mastery of plants to the next generation.

Tropical rainforests house hundreds of thousands of species of plants, many of which hold promise for their compounds that can be used to ward off pests and fight human disease. No one understands the secrets of these plants better than indigenous shamans — medicine men and women — who have developed boundless knowledge of this library of flora for curing everything from foot rot to diabetes. However, like the Amazon rainforest itself, this is rapidly changing. As forests fall to loggers, miners and farmers, and the allure of Western culture attracts younger generations to cities, extensive knowledge of the forest ecosystem and the secrets of lifesaving medicinal plants are forgotten. The combined loss of this knowledge and these forests irreplaceably impoverishes the world of cultural and biological diversity.

ACT is working to avoid this fate by partnering with indigenous people to conserve biodiversity, health and culture in South American rainforests. Plotkin, a renowned ethnobotanist and accomplished author (Tales of a Shaman’s Apprentice, Medicine Quest) who was named one of Time magazine’s environmental “Heroes for the Planet,” has lived and worked with shamans in Latin America since the early 1980s. Through his experiences, Plotkin has concluded that conservation and the well-being of indigenous people are intrinsically linked — in forests inhabited by indigenous populations, you can’t have one without the other. Plotkin believes that existing conservation initiatives would be better served by having more integration between indigenous populations and other forest preservation efforts.

ACT is working to build stronger cultural ties between tribal elders and children. Under the “Shamans and Apprentices” program, elder shamans pass on their expertise of medicinal plants and healing rituals to apprentices, children who are otherwise increasingly distant from their culture.

Shamanism is a product of accumulated knowledge of past generations as well as deep ties, spiritual and physical, to the natural environment. But in a world where forests are being rapidly destroyed and profound cultural transformation is occurring among younger generations in traditional societies, the healing knowledge of shamans is disappearing. Among the Trio, the trajectory was accelerated by the missionaries who initially demonized shamanic practices, ostracizing healers from their communities and leaving an entire generation without the traditional apprentice/mentor relationship that is the basis for passing on knowledge from tribal elders to youths.

ACT has established a system of traditional health clinics to improve health care and promote medicinal plant knowledge among younger members of the tribe by bridging the gap between youths and healers.

But while seeing ACT’s work was inspiring, the weather issue that delayed my arrival was becoming a worry.

On my second day I noticed that no plane had arrived. I assumed that was normal; after all, how much air traffic does a remote outpost in the Amazon receive?

The next day was the same, no plane. But this time there was gear on the airstrip that looked like it was awaiting shipment. Then I heard Melvin complain that air traffic control in Paramaribo thought it was flooding here and was blocking service.

It had rained in the middle of the night, a torrential downpour, but the ground was dry and the skies clear. I walked around the airstrip. The ground was hard and I didn’t find any swampy areas.

This could be a problem. If air controllers were making sweeping assumptions about the conditions on the ground here, we could potentially be stuck here for quite a while.

Apparently air traffic control was on edge after a plane crash a few weeks earlier had killed 17 passengers. They weren’t taking any risks. Because the weather maps showed rain in the region, the assumption was it was too dangerous to fly.

Normally I wouldn’t be too concerned about the prospect of being trapped in the forest a few extra days, but this time was a little more inconvenient since it was the end of my trip and the plane ticket from Suriname would be rather expensive to change. I also had upcoming meetings in San Francisco I hoped not to miss. But I still had a few more days; maybe Paramaribo would relax a bit or the “weather” would let up.

The next few days I saw other aspects of ACT’s work like its indigenous park guards program. I also spent time with Amasina, a Trio shaman, try to learn more about how he diagnosed and treated disease. At the moment he was treating a very sick Dutch woman, for whom doctors said they had done everything they could. She had come here as a last resort.

She described the way he looked into her eyes and touched her in a comforting and knowing way. Amasina had no prior knowledge of her conditions, yet he immediately identified her illness as originating in her liver, which was accurate. She was surprised when Amasina told her he had seen much worse and that she would get better.

Ethnobotanists, people who study the relationship between plants and people, have long been aware that rainforest dwellers have an astounding knowledge of medicinal plants.

For thousands of years, indigenous groups have extensively used rainforest plants for their health needs: the peoples of Southeast Asian forests used 6,500 species, while Northwest Amazonian forest dwellers used 1,300 species for medicinal purposes. Today, pharmacologists and ethnobotanists work with native healers and shamans in identifying prospects for development of new drugs. The yield from these efforts can be quite good — a study in Samoa found that 86 percent of the plants used by local healers yielded biological activity in humans — and the potential from such collaboration is huge, with approximately one half of the anti-cancer drugs developed since the 1960s derived from plants.

Perhaps more staggering than their boundless knowledge of medicinal plants is how shamans and medicine men could have acquired such knowledge. There are over 100,000 plant species in tropical rainforests around the globe, yet how did indigenous peoples know what plants to use and combine, especially when so many are either poisonous or have no effect when ingested? Many treatments combine a wide variety of completely unrelated innocuous plant ingredients to produce a dramatic effect. Some, like the curare of the Amazon, are orally inactive, but when administered to muscle tissue are lethal.

No one knows how this knowledge was derived. Most say trial and error. Native forest dwellers say the knowledge was bestowed upon them by the spirits of the rainforest. Whatever the mechanism, evidence from Amazonian natives suggests that indigenous knowledge of medicinal plants can develop over a relatively short period of time.

Ethnobotanists studying medicinal plant use by recently contacted tribes like the Waorani of Ecuador and the Yanomani of Brazil and Venezuela reported a relatively limited and highly selective use of medicinal plants. They had plants for treating fungal infections, insect and snake bites, dental ailments, parasites, pains and traumatic injuries. Their repertoire did not include plants to treat any Western diseases. In contrast, indigenous groups with a history of continuing contact with the outside world have hundreds of medicinal plants used for a wide range of conditions. It seems that after contact, in response to the introduction of Western diseases, these tribes accelerated their experimentation with medicinal plants. This notion contradicts the idea that indigenous knowledge of medicinal plants was accumulated slowly, over hundreds of years.

The knowledge and treatments of shamans is the product of their own scientific method, accumulated from a progressive cycle of trial, experiment and observation repeated over countless generations. It may not be published in Science or Nature, but in many ways is fundamentally based on the very same empirical and pragmatic principles as Western medical science.

Shamanism is a product of accumulated knowledge of past generations as well as deep ties—spiritual and physical—to the natural environment. But in a world where forests are being rapidly destroyed and profound cultural transformation is occurring among younger generations in traditional societies, the healing knowledge of shaman is disappearing. Among the Trio, the trajectory was accelerated by the missionaries who initially demonized shamanic practices, ostracizing healers from their communities and leaving an entire generation without the traditional apprentice/mentor relationship that is the basis for passing on knowledge from tribal elders to youths.

As the days passed I grew more concerned about my impending international departure. It was looking bleak. Each night would be clear and I would go to bed thinking tomorrow the plane would come. But each night I was awoken by the sound of distant, but approaching rain. The din would grow louder into a thunder and then crescendo as a roar — immense buckets of water pouring down on the thatch roof. I’d hear the water rushing; the bare ground around the hut becoming a river. Eventually I would fall asleep. By morning, when the drone of the rambling announcements made over a distant loudspeaker by the village chief would begin, the only sign of the deluge would be a higher waterline in the swampy area behind the hut. The grass airstrip would again be dry. Yet again, no airplane.

The same events unfolded each day and it was clear we wouldn’t get back to Paramaribo in time for me to catch my flight home. ACT had a satellite phone, so I was able to alert the airline that I would need to postpone my flight home. That process was like something out of a slapstick comedy: the phone only picked up decent reception in the middle of the airstrip under the baking sun. The ticketing agent would put me on hold before giving the final confirmation. Each time I was put on hold I would lose the connection. It was infuriating. Eventually I figured out another approach: I called my mom at her travel agency and asked her to handle the arrangements.

We had only brought enough food for five days and were starting to run low on some of the rations. Because the water levels were high from upstream rain, some of the manioc fields were flooded and fish were hard to catch, making food scarcer than usual in the community. But we still had a decent supply of hot dogs and rice.

At this point I still hadn’t had much of an opportunity to get into the forest. The uncertainty with the itinerary meant we had to stick around Kwamalasamutu in case a plane miraculously appeared. As it was, we were constantly scanning the skies in the hope salvation would come.

One of the reasons I had come to this part of Suriname, beyond wanting to see ACT’s work, was to try to find the dyeing dart frog. This wasn’t just any old frog, it has electric blue and yellow patterns. The colors advertise its toxicity to predators. Related species have been used by indigenous populations to poison the tips of darts and arrows. The toxin paralyzes the respiratory system. Because it isn’t orally active, it doesn’t poison the flesh, which can thus be eaten.

The indigenous park guards knew where to find this frog, but it was four hours by dugout canoe. Since the airplane status hadn’t changed in a week, I decided to chance it and go frog-seeking the following day. At least barring a rainless night, of course.

After yet another night of rain, starting about 1 a.m., I met Jonathan and Juan, Trio men employed by ACT, by the river. I carried my camera, each had a shotgun with a shell, and there were gill nets in the boat. This would be a joint patrol and hunting trip.

As we went upriver they laid nets along the vegetation. The river was muddy and swollen from the unusual amount of rain. Some of the trees were submerged up to their lower branches.

After a few hours in the dugout we reached our destination, a swampy area. We put on boots and set out into the forest. Not speaking much Dutch or Trio, communication was mostly limited to gesturing and the few words we knew in each other’s languages. Jonathan was taking me to look for frogs. Juan was going hunting. After a few minutes we encountered the first dyeing poison dart frog. As expected, it was beautiful. There were a lot of frogs in the forest. Most were in the leaf litter, but a couple had a tadpole on their back and hopped directly up the vertical tree trunk toward the canopy. Once they got there they would deposit the tadpole into a pool created by the upturned leaves of a bromeliad. The mother would return regularly, repeating the arduous trip up the tree drunk to deposit an infertile egg as food.

My observation of one of the mama frogs making this journey was interrupted by a sharp whistle, then the boom of a shotgun. Jonathan shouted something, then started running. I followed him, but struggled to keep pace with my camera and lenses in hand, height, and lack of forest agility compared to the locals. Vines, spiny plants and small hanging nests didn’t help.

After about 10 minutes on the run we came across Juan, who was staring up into the canopy. There were droplets of blood on the plants around him.

After a moment I spotted what he was watching: a red howler monkey. Juan had used his one shell to shoot the primate, which was now moving around agitated in the canopy. In the shadows above it I could make out some other howlers, which were also watching.

As the howler lost blood, it moved less and dropped lower down the canopy. After about 20 minutes it climbed onto a liana that nearly reached the ground. Juan shook the vine violently and the monkey tumbled to the ground. It tried to run away but Jonathan grabbed it by the tail. He proceeded to bludgeon it with the blunt end of the machete. All the while a bigger monkey watched. It descended the canopy to observe the fate of its companion. Its expression forced me to look away.

Jonathan and Juan made quick work of the monkey, converting it into what could be compared to a backpack. As we made our way to the canoe, the dead monkey stared at me, its head bobbing up and down.

As we moved from the cathedral-like primary rainforest with its towering trees and relatively sparse understory to the swamp forest, the vegetation grew thicker and more tangled, necessitating the use of machetes. Hacking through the underbrush is not easy work. It requires strength, stamina, patience, and quick reflexes to dodge the critters that may be disturbed by the slashing: wasps, centipedes, spiders, biting ants, and snakes.

I was walking behind Jonathan and Juan, careful to avoid the swinging blades. But then in an instant a piece of wood splintered from a machete hack shot into my eye. I cringed as I felt my contact lens move high up my eyeball. While the lens had protected my eye against the impact, it had been dislodged to a place it didn’t belong. My day had suddenly gotten a whole lot worse.

Jonathan and Juan continued chopping through the understory and I followed them. There was nothing I could do here about my eye. We found the canoe and paddled out of the swamp and into the river.

On the way back, Jonathan was fixated on “sweet meat,” which was apparently a reference to iguana, the large vegetarian lizard that often hangs out in trees along rivers. He had one shotgun shell remaining.

Jonathan stood in the front of the boat on iguana patrol. He spotted a few but each time they dove into the river before he could take aim. Meanwhile the dead monkey continued to stare at me through its vacant eyes as I used my macro lens to try to take self-portraits of my eye in an effort to assess the damage. It was very red and there was no sign of the contact — which was a hard lens. I was hoping to at least see an edge so I could try to remove it once I got back to Kwamalasamutu.

We would stop at the sites where the gill nets were laid. The pickings were slim. The nets only contained a few fish, but Jonathan and Juan would toss each one no matter the size into the bottom of the boat. The fish would flop about. Some made sounds: the catfish would chirp or make grinding noises.

Jonathan spotted a big iguana in the top of a tree. This time he was careful and we took a stealth approach, concealing ourselves in some vegetation until he was within range. Jonathan stood up, took aim, and fired. It was a direct hit, and the iguana fell onto a branch just inches above the ranging current. Jonathan collected his prize, which was added to the collection of fish and my dead monkey friend, who was now attracting quite a number of rather large flies.

We came to another fishing net. As Jonathan and Juan untangled it, a plane flew over. My heart raced. Could this be my rescue? How far were we from Kwamalasamutu, I asked Jonathan. But the message didn’t get across. There was nothing I could do at that point. Hopefully the plane would wait for me.

Then Jonathan noticed my eye. He could see something was clearly wrong. I explained and managed to convey that something — I didn’t bother trying to explain the concept of a contact lens — had gone into my eye. He looked concerned, then started to move his finger, still stained with monkey blood, toward my eye. I quickly said we could wait until we got back to Kwamalasamutu. He seemed to understand. The last thing I needed at this point was an eye infection while trapped in a remote Amazon forest.

About two hours later we reached Kwamalasamutu. There was no plane. It never landed. Hopes crushed, I went to go find my travel mirror to see if I could locate the contact in my eye.

I was unable to see it but I could certainly feel it. My eye was looking pretty nasty but I’ll spare you the details. The ACT people took a look but came up empty as well. Even Amasina checked, but he found nothing.

That night I lay awake suffering in my hammock. It was especially hot. Sweat dripped down my brow. Would it rain again tonight? I waited for the dreaded sound. One a.m. came, but still no rain. Maybe this was my break.

I dozed off only to be awakened by a thunderous downpour, more vicious than any we’d experienced yet. It was accompanied by deafening thunder that shook the ground. We weren’t going to be flying out that day.

In the morning my eye was throbbing and looking disgusting. I exhausted every idea: opening my eye underwater, flooding my socket with artificial tears, rolling my eyeball and flipping my eyelid inside out — nothing worked. No one could see the lens, but I knew it was still in there.

Melvin and I spent the day trying to convince air traffic control via radio that the airstrip was fine for planes. We weren’t successful.

We used up the last of the hot dogs, sugar and tea. We only had rice left.

Another night came and went. Rain again.

The next day our hopes were raised. A rumor spread that a plane was coming. Sure enough in the afternoon, a plane circled overhead. We were relieved. But it didn’t land. More waiting.

Having failed in the appeal to the authorities in Paramaribo, I sought more drastic measures. I went to Amasina and asked about the possibility of a no-rain dance. To my disappointment, he said it was going to rain again that night.

But then Amasina told me something really interesting. He said rain patterns had shifted dramatically since Mark Plotkin had first arrived in Kwamalasamutu. Floods were worse now, while the dry season was more severe. He didn’t know what caused the change, although he didn’t blame Mark for the development.

That night, as Amasina predicted, it did rain — the same deluge as the night before.

I awoke to the usual banter at 5 a.m. from the loudspeaker. Feeling glum, I rolled out of my hammock. My eye was especially gritty and gross that morning.

I went out to look at the airstrip; no change, it was still there. I went behind the hut. The water level in the swampy area had risen considerably overnight. The outhouse was now partially underwater. I went into the kitchen. The rice supply was looking pretty meager. Not a great start to the day.

Melvin then shouted “Good Morning.” I turned around. He was beaming. The loudspeaker announcement this morning said a plane would be coming to Kwamalasamutu.

Impossible. I didn’t believe it. I wasn’t going to let myself get set up for disappointment yet again.

But this time was different. People in the community were bustling and Melvin himself was packing up his things. Maybe this really was going to happen today.

In the event we were going to make it back to Paramaribo, I was going to need medical attention, preferably an ophthalmologist. So we called ACT headquarters. They would make an appointment for me.

We waited anxiously. Hours ticked by. Then we heard a wonderful sound: the buzz of an airplane. It circled one, twice, and then it landed! Rejoice!

A couple of passengers disembarked. The pilot spoke with Melvin. Their voices grew louder and more urgent, accompanied by gesturing. The pilot stormed over to the plane and got inside.

Melvin came over to explain the situation. The pilot said he only came to drop off passengers; he didn’t have enough fuel to carry people back to Paramaribo. Maybe there was another plane on the way.

The news wasn’t welcome. Melvin went back to negotiate with the pilot and was joined by community members. The conversation stretched on for 20 minutes, and then 40. Was this a stalling tactic to see if another plane was going to arrive?

Melvin walked over to me. A decision had been made: all five of us were going to squeeze into the plane.

That was an abrupt change. I wasn’t sure what to think. After all, if the pilot didn’t have enough fuel for any passengers, why would he suddenly be able to carry five plus gear? I wasn’t going to question the decision, however. I didn’t have all the information. I needed to get back to Paramaribo to get my eye examined. I was sure the pilot knew what he was doing.

We climbed into the Cessna and rolled down the runway. The plane accelerated but wasn’t lifting off. We must have been overloaded. Ahead of us loomed a wall of rainforest. Were we going to make it?

As we neared the trees we finally lifted off, just clearing the canopy, before coming down low over the river. We were close enough to see the ripples. Slowly we built altitude over the river and then turned back over the forest. We were on our way.

The flight was nerve-racking. There were towering thunderheads and some rough patches. The fuel gauges were precariously low by the time we finally started to see the first signs of civilization. We seemed to be flying on fumes, but we made it to Paramaribo.

Upon arrival I received some unhappy news: there had been no luck in arranging a doctor’s appointment. It was Friday and most of the doctors had gone home after lunch. But I could try the emergency room.

That wasn’t exactly what I had in mind, but Paramaribo had to be better than Kwamalasamutu for getting eye treatment. As we headed toward the hospital, the phone rang. Melvin had found an optometrist who could treat me at his home office. So we went straight to his place.

There I was met by his wife, who said he would be home shortly. She could tell I had been through a lot, and offered me food, drink and the hand of one of her daughters.

After a couple of hours, the doctor finally came home. He led me down to his basement where he had an office. He had clearly been in the eye business for a long time — the room was full of all sots of instruments of torture that looked to date from the 1950s or 1960s. But reassuringly there was an eye chart and an examination chair.

I saw down and explained to him the problem. An immediate concern was that though he spoke perfect English and was an optometrist, he didn’t seem to know what a hard lens was. He asked me to get in the examination chair and looked into my eye.

“Nothing there,” he said. “Is it the other eye?”

My confidence not inspired, I told him he had the correct eye, but that the contact was very high.

“OK,” he said. He prodded some more. And finally, “I think I can see it way up there. Maybe.”

“I need to strap you in.”

He strapped down my wrists and braced my head with a clamp. He took a pliers-like device from a drawer.

I could tell this was going to be unpleasant so I turned my mind elsewhere. I thought about my time with Amasina, the moments in the forest, the monkey, and those beautiful frogs that had seduced me into this situation. Then it was over.

“There it is,” he said as the contact landed with a light “click” somewhere on the linoleum. He unrestrained me and I jumped up, giving him a big hug. I was overjoyed. He was bewildered by my reaction. I paid him, thanked his wife, and went on my way.

The next day I was feeling great. So good the 3 a.m. departure for the airport didn’t bother me. Nor did my missed flight out of Trinidad due to incompetence at passport control, nor the godforsaken but pricey airport hotel with a human-shape stain on the carpet and a bathroom floor flooded with black sludge. I had survived Suriname with vision in both my eyes. That was enough for me.