I braved spiders, snakes and stinging ants in Costa Rica’s rainforest

I’m cooling off in the jacuzzi on the terrace of our 10-metre-high treehouse when I hear a soft rustle of leaves in the sotocaballo trees next to me. Then comes a heavier thrashing as the branches bend and sway, and a large spider monkey - reddish-brown-bodied with black gangling arms - swings in front of me. It leaps casually from tree to tree, its tail a fifth limb clinging to the branch behind as it stretches ahead, sometimes jumping metres down, its fall broken by branches beneath. Another comes, following a similar path. Then another - a mother with baby clinging to her chest. Then the canopy is still again, and I can’t stop smiling.

I’m relaxing in Boca Tapada, a remote nature reserve in northern Costa Rica, quite literally forest bathing. Earlier in the week, in Tortuguero on the Caribbean side, spotting wildlife was much harder work.

It’s 6am, and I’m in a canoe with Antonio our guide, sporting goatee and backwards baseball cap. The air is fresh, river silent but for a distant motorboat and slap of oar. We paddle slowly around the forested Isla Cuatro Esquinas. Antonio notices a sloth in the trees, although I can’t see it. Apparently they can swim. “You’ve seen a dog. Sloths swim that way, but maybe ten times slower.”

We find an inlet between low-hanging fig branches and edge through, nervously pushing aside huge yolillo palm fronds. When the canoe grounds Antonio steps out, unfazed, to push us off. "There are no piranhas here,” he laughs, “but we have their cousins - machacas. They don't attack people, only bite your finger.”

The river is good for spotting birds; vultures and green ibis, and we’re lucky to observe bottlenose dolphins, drawing silent curves in the water beside us. But it's the howler monkeys that grab me. We hear them first, a drawn-out ululating yawn, then the reply from the far side of the channel; howler calls can be heard over a mile away. We glimpse three dark-brown figures crouched on a treetop, thick tails curling underneath, oblivious to us.

Later, we explore the rainforest on foot for a close-up look. The path is wet so our first stop is the village wellington boot-hire lady. She takes one look at my feet: “43”, she announces. Spot on. The trail is quiet, enclosed above by tall gavilán trees whilst arching palm fronds, weighted with rain, crowd from the side. It’s a chance to find smaller creatures, and I notice a bright yellow snake curled on a palm leaf, just off the track. I lean forward to study horn-like scales above each eye. “That’s an eyelash palm pit viper,” Antonio explains. “Highly venomous.” I step back sharply. He explains how his father used to kill dangerous snakes to protect his family, but now all are protected throughout Costa Rica.

We track more monkeys, spider and the smaller capuchin, and spy toucans high in trees. Then Antonio stops. “Papa said first you hear it, then you smell it, and maybe then you see it.” The rapid “che-che-che” is clear from our right, and I spot the bright red, thumbnail-sized frog - the “blue jeans” poison dart frog - throat pulsing as it chirps. Then it’s gone.

We walk through the village returning to our lodge, passing Antonio’s “humble house”, as he puts it, a simple wooden lodging; him waving to his aunt as the rain restarts. Like most guides here, Antonio grew up in the village and tells of the shift to conservation first-hand: how his family used to hunt in the forest, and now they’re sustained by it.

We head out at twilight on a night walk, hoping to spot nocturnal animals. We’re each given a torch and follow a boardwalk threading through the darkening forest, pools of water beneath. It’s narrow and feels precarious, with only a wire strung along the left for support.

“Keep hands inside and look before you touch,” our guide Gabriel warns, shining his torch on an inch-long, bulbous bullet ant - one of the most painful stinging insects - crawling along the handrail. I notice wolf spiders too, and fear walking blindly into a web.

We study lizards, vipers (one shedding skin) and huge, beautiful webs, spiders at their centres. I’m drawn to the frogs, particularly the red-eyed tree frog sitting on a philodendron leaf - its tiny, vivid green body contrasting with bright red eyes - and, more unusually, a Palmer's tree frog, pale and near-translucent.

Midway, we turn off our torches and the night turns black. “This is normal for the animals,” Gabriel remarks, their other senses compensating in a way ours cannot.

Leaving Tortuguero by boat, we travel west to Maquenque, in Boca Tapada. I’m thrilled to see keel-billed toucans, hummingbirds darting flower to flower, and once, low over treetops, the lapa verde - the rare great green macaw.

Costa Rica now protects over half its land as forest, paying landowners to preserve rather than clear, and that philosophy is clear when we speak to the lodge’s founder, Eduardo, a farmer turned conservationist. Aged 78, white hair immaculate, he sits next to the manager, his son Julio.

He talks of setting up the eco-lodge. “First decision: don’t continue cutting trees and don’t kill the snake. Because tourist, they like to see. So we move the snake; we don’t kill,” Julio translates. I ask Eduardo what he values most about the forest. “He loves the quiet and also enjoy the natural springs,” Julio replies, then adds: “It’s the time in May of a lot of fruits in the forest. We have a lot of babies of monkeys, reptiles, amphibians.”

Eduardo expands on his passion: the lapa verde. One of the largest macaws, with brilliant lime-green feathers and a flash of scarlet across the forehead, it’s critically endangered. Before we leave, he reaches for his guitar and starts to sing, unselfconscious; his voice clear above the gentle strumming. Julio translates the song telling of the macaw's flight over almond trees, across the border into Nicaragua, before its ending refrain - a promise. “Lapa verde es como las cuidamos. Nunca, nunca se van a extinguir. Green macaw, we take care of you. They will never, ever become extinct.”

Maquenque Eco Lodge (maquenquelodge.com) has fabulous treehouses high in the forest canopy, offers a full range of nature tours, and can arrange transport from around the country. In Tortuguero, Mawamba Lodge (mawamba.com) offers comfortable bungalows overlooking the river within walking distance of the village and will also organise transfers and guided nature tours.