When evening fell on our first day in the jungle, it was time for the night hike.

The rainforest is completely different at night. It’s like the insects and furry animals that live beneath its canopy suddenly clock out at 6pm, changing shifts with a horde of slimier, gooier, spindlier creatures.

We were advised to buy head-torches ahead of the tour, but I refused because I didn’t want to waste money on something I’d only use once. Instead I used my phone torch, with my phone zipped in a translucent plastic bag Nataly gave me. I placed it in my shirt pocket, peeking out to illuminate my way. It didn’t work astonishingly well, but it gave me enough light to find my way.

We left the hut, and the monster sightings began at once. We’d not even crossed the clearing and entered the jungle when Alain stopped us, shining his head-torch beam at a tree trunk a few metres away.

“Look,” he whispered.

A black tarantula the size of my entire hand was perched on a tree. Oddly, I didn’t feel shocked, or unsettled. I didn’t feel remotely afraid of anything we saw on the night hike, actually. It all felt too bizarre, hyper-real and surreal at the same time, like when you wake up in the middle of the night to go to the bathroom and you’re still half asleep and fresh out of a dream and everything is just a little bit trippy.

“So are tarantulas, like, king of the bugs in the jungle?” I asked Alain.

“Tarantulas? No. Lots of things eat tarantulas. The queen of the bugs is the wasp, man. She kills the tarantula, she stings him and lays her eggs in him, then her babies eat him. Nothing eats wasps.”

Not for the first time, I felt a strong desire to be somewhere very clean and cosy and dry and lit with a nice log fire.

We’d not been in the jungle long when Alain, walking at the head of our group, saw something in the darkness. It happened in half a second: he looked away to the left, gasped, drew his machete and sprinted off the path. The Israeli boys hurried after him, and Nataly and I jogged in last – just in time to see Alain thwack a tall bamboo shoot in half, cutting off any potential escape route of the sloth he’d found clinging to it.

Without a pause he sheathed his machete, took the sloth under its armpits and lifted it from the severed bamboo shoot. It didn’t want to let go at first – Alain had to tug it and unwrap its claws from the branch. Nataly didn’t like this.

“You’re stressing it, leave it alone. You’re stressing it!”

I felt a bit annoyed that she said this. It took a very mad, magical moment and spattered it with useless millennial guilt. The Israeli boys, however, took a different stance.

“Can I hug it?” asked the young one, not perturbed in the slightest by Nataly’s protests. “Here, pass it here.”

I don’t know where I stood on the issue really; whether it was fine or not to pick up a wild animal. I wasn’t overly fussed, to be honest. Alain wasn’t hurting it. I was just happy to see a sloth at all.

It was as big as a housecat, with a stoned expression and one of those short, choppy fringes that everybody in Berlin has. Its fur was matted and thick and shaggy, an odd greenish-brown colour, and covered in hundreds of moths that flew away when Alain picked him up.

If memory serves, nothing eats sloths because they taste horrible. I would like to add to this my own theory: that nothing eats sloths because they look horrible. Imagine you were a cannibal, and you were looking around for a human to eat. Would you choose someone clean-looking with a healthy glow to them, or would you prefer the slack-jawed, hair-matted freak sitting in the park covered in bugs, staring at his hands and drooling?

Exactly. Nobody would eat the goggle-eyed shit-pants weirdo. They would be safe. Evolutionary genius.

*****

Clambering over the floating bamboo logs in the marshy areas of the rainforest was more difficult in the dark, especially with all the moths and mosquitos and sandflies that were continually zipping into our eyes and mouths on account of the head-torches.

Deeper in the jungle we saw more tarantulas, scorpions, and other strange insects with antennae poking out from inside dark, webby holes in tree trunks. We also saw a bullfrog, the largest frog I’ve ever seen. It was the size of my head, and it had red eyes. It hopped away in one great bounce after staring into our torch beams as though hypnotised.

We were hoping to find a snake or two, but the sudden outbreak of a storm forced us to head back. Alain told us storms send branches crashing down from high above, which can be deadly. In a hurry, then, we raced back through the jungle, with the water level in the swamps and quagmires rising at an alarming rate. All I remember of that panicked half-hour is the desperate muddy suction of deep puddles, the gleam of swinging light beams on wet leaves rattling beneath the downpour, and the regular horror of a sudden up-sweep of torchlight illuminating spiny branches inches from my face.

*****

I slept strangely, hemmed in by mosquito net, listening to growls and hollers from the undergrowth around the hut.

The next morning we ate a hearty breakfast and set out on a 2-hour jungle hike to see some gigantic, ancient trees. By day the forest is less intimidating, though it remains hostile, always. While playing ‘Tarzan’ on a dangling vine we found, one of the Israeli boys disappeared down a two-foot wide hole in the forest floor, the vertical height of a man. He was fine but a little shaken up; there was no reason for it to be there.

We saw tiny monkeys and enormous trees, and returned all sweaty and exhausted to the hut for lunch: rica, pasta, salad, chicken.

As the afternoon grew late on on our second day, we clambered down the ladders on the bank – which had eroded several metres in one day, meaning the ladders had to be repositioned – and boarded the boat. After the previous day’s hour-long dolphin-seeking stint – which had been composed of approximately four minutes of actual dolphin watching and fifty six minutes of cruising vaguely up and down the river with Alain going ‘I’m sure they were around here somewhere’ – we’d gotten wise to the potential tedium of animal spotting, and consequently had come armed with snacks and cigarettes to pass the time.

We glugged up the river, stopping for half an hour at a beautiful village on a green bank, all colourful and wooden, all on stilts. Alain had some business to attend to there, and we were free to schlep around in our wellies and say a smiley ‘hola’ to the children who came out to look at us. Nataly and I were similarly astounded as to what different lives these children led to anything we knew. Home felt very far away.

*****

A mile on, up a 50-metre wide tributary overhung with old vines and dipping boughs, our boat came to a stop. Alain handed out fishing rods: long, thin branches with fishing line tied on one end. On the other end of the fishing line was a hook with a piece of raw chicken. There was no speech or lesson on how to fish. Alain just handed us our rods and told us:

“Now we fish for piranhas.”

It’s quite a weird feeling, knowing that the overladen boat you’re on is floating half a metre above an unseen piranha horde; that all that separates you and them is about two centimetres of seen-better-days wood. It’s an even weirder feeling to lower your bait into the water and almost instantly feel the tugging nibbles of a thousand jagged little teeth. But the water was too murky, and I could see nothing – only imagine.

Alain told me piranhas don’t hook themselves when they take the bait – perhaps other fish do, I don’t know. With piranhas, you have to wait until you feel a nibble then yank the hook up hard from the water, hopefully hooking the roof of the fish’s mouth in the process.

I got many bites but caught nothing. Nataly caught a catfish, the outdoorsy Israeli guy caught some weird fish that looked like a piranha but wasn’t, and finally, the driver of our boat – he was skinny but very handsome, looked like a tiny Amazonian Brad Pitt, didn’t speak much – caught a piranha. It was silver and the size of my palm and very ugly. I thought we might take it home to eat, but he released it back into the river.

*****

And now it’s sunset on the river, and the fish have stopped biting, and we are prodding Alain to ask what we’re going to do next. Alain doesn’t like being asked this, and keeps telling us to be patient. We have to wait for darkness.

Our little boat chugs away upriver, and the waters narrow and grow dense with reeds and vines that hang over the water. The sky turns black and we leave this narrow stream to enter what looks like a great expansive swamp; lilypads float on the surface, and black trees far off ring the periphery. Two hundred metres away, we see the silhouette of an old house on stilts, orange lights in its windows. I think of the word ‘bayou’.

The stars above are a great silver thumb-smudge across the sky. Alain gestures for the driver to kill the engine, leaves us floating.

“Amigos, now we go to catch a cayman. Now a crocodile, not an alligator, a cayman. The babies are a metre long, the adult black caymans, up to six metres. We will try to find a young one.

“Now, I need you to turn off your torches. No lights at all, and quiet. There is only one way to spot a cayman in these waters. Do you know what it is?”

Nobody does. Alain taps the headtorch on his forehead, and it switches from white light to red.

“The eyes. They reflect.”

Alain nods to the driver, and with the engine on low, our boat moves off through the reeds. The water around us is black and still, and Alain stands on the wooden prow, one foot resting on the gunwale, the red beam of his gaze sweeping slowly across the lilypads. It does not take long.

Alain sees something. He hisses to the driver, and the engine shuts off. He waves to us, and one by one we stand to join him and follow his gaze. Twenty metres off, almost completely hidden by floating grasses, is a golden twinkle. It is the eye of a cayman, one inch above the water.

We don’t catch this one: it hears us coming and flees. We don’t catch the next one either, or the next. We smoke cigarettes in the dark. We grow restless. Mosquitoes bite. The young Israeli asks if anybody else wants to go home – we all say no.

And then Alain sees something: more eyes in the water, close by. He removes his t-shirt, throws it behind him into the boat. The driver moves off, engine chugging – too loud, I think, we’ll never catch anything. I watch the silhouette of Alain on the prow, yellow moon in purple sky, torch beams sweeping over red reeds. He watches something in the water – something we can’t see. As we idle, around our boat I see blue flashes, twinkles. It’s fireflies, I realise, and the air around the lilypads and the reeds sparkles as they wink in and out of existence like magic.

I’m watching the fireflies when there’s a splash – rough, frantic – and I see Alain laid out, both arms plunged into the water, teeth bared in concentration. Finally with a grunt he heaves and rolls onto his back. He sits up – and he’s holding a cayman.

It’s a baby, a metre long. It thrashes at first, then calms, reptilian eyes unmoving and unblinking. Alain teaches us of its teeth, its claws, its strong tail. I touch its spiny back and its soft belly. You can only catch each cayman once, says Alain. After, they never trust the sound of a boat. No human will touch this animal again.

And then we say goodbye to the creature. Alain releases it into the water and it slashes away into the dark. We switch on the engine, and we gurgle back home, down the warm black waters of the Amazon.