Arriving at San Jose airport, a couple of hours' onward flight from Miami, I see an English lad in the passport queue, deep in a book on reptiles.
"What will Miss say when she finds an iguana sitting in your seat next term?" his parents tease him, resigned to the idea that their son wants to become a reptile. But what does Costa Rica offer a tourist like me, who is terrified of snakes and not particularly outward bound, especially in the British school summer holidays, the "green" season when the rainforest is at its rainiest? And is it worth the long journey for other, less herpetologically obsessed families?
Alison Scott, head of Wadworth primary in Doncaster, on a fortnight's holiday with family and friends, was attracted by Costa Rica's 95 per cent literacy "and the fact that all the electricity's green". The country's two centuries of democracy and its advanced health service, funded by savings it made when it abolished its army in 1949, are other pluses for many travellers looking to put a first foot in Latin America.
I meet Alison's small group taking shelter from the rain and eyeball to eyeball with the red-eyed tree frogs in the Ranario Frog Pond just outside the Monteverde Cloud Forest Reserve, high in the mountains that form the spine of the country. Their trip has already taken them to Tortuguera national park on the Caribbean coast, where she says the children walked for two hours in the rain "because there was so much to see".
Staying in a comfortable wooden cabin at Tortuguera's Pachira Lodge, I found a pair of toucans outside my door and a two-toed sloth drying itself after breakfast in the sunlit high branches of a tree next to the restaurant. For Alison's daughters Sarah, 13, and Sophie, "nearly nine", the highlight was the night vigil on the beach at Tortuguera to see the green sea turtles laying their eggs.
You do not need to be an expert or to rough it to encounter Costa Rica's wildlife. "A gaudy leaf frog crawled all over Sophie's head by the swimming pool in Tortuguera," says Alison. At Fonda Vela hotel in Monteverde, an armadillo noses around my feet. After I've finally seen a (very small) boa constrictor in Manuel Antonio national park on the fringes of the Pacific, I am able to recover on the beach next to a pair of sunbathing iguanas and a coatimundi coveting the bananas in a holidaymaker's bag. Every day seems to provide sunshine along with the rain.
It's worth venturing into the forest early when the howler monkeys begin their eerie morning booming. With 12 of the world's 24 microclimates and 25 per cent of the country designated as national park, Costa Rica is a wonderful place to relax with nature. The tourist guides, government-regulated and highly trained, ensure that visitors see the best of the country, while disturbing the plants and animals as little as possible.
You don't need to be particularly fit to walk up to the ridge in the Monteverde Cloud Forest. The land slopes down to the Pacific on one side, the Caribbean on the other, and giant Blue Morpho butterflies, big as tea plates, flutter in the treetops below. We spend a day walking on hanging bridges and rainforest walkways that skim lightly past waterfalls and trees with aerial roots like wine-bar candles. It's almost too easy. I don't have the excuse of aching muscles to relax in the rock-star glamour of Tabac"n hot springs, a lush pool complex of waterfalls and streams with a swim-up bar.
Best to breakfast lightly before taking one of Costa Rica's zip-wire rides through the forest canopy. I try the Sky Trek at Arenal, buckled into a climbing harness and sliding across the valleys almost 200 metres above the forest floor. They say we reach speeds of up to 64kph: this is what it feels like to be a spider monkey. Later, over dinner at the Hotel Arenal Kioro under the volcano, we watch red lava sizzle down the mountain in the dark.
My cheerful guide, Diego Arce Perez, is keen to show me history as well as wildlife. The Centro Neotropico Sarapiquis is a hotel built on ecological principles with an archaeological site in its back garden. We stay in modern rooms within huge round, thatched buildings that are copies of the communal homes that were common in pre-Colombian times. The garden has ancient species and medicinal plants, while next to the dig another thatched building houses a museum dedicated to the culture of the region's indigenous peoples.
As traditional music floats on the air and mist swirls across the landscape from the neighbouring Tirimbina biological reserve, the past comes indelibly to life. Strangely, there is some of the same atmosphere at the hip 'n' happening Xandari resort and spa, on a coffee plantation in the hills near San Jose. The villas are arty and modern, but the way they sit in the landscape, encouraging guests to contemplate the hummingbirds, is timelessly Costa Rican.
CTS Horizons (020 7836 9911; www.ctshorizons.com) offers a range of Costa Rican itineraries, including private journeys of varying durations. As an example, its 13-day 'Rich Coast' tour costs pound;2,095 per person this summer based on two people travelling and includes return flights with British Airways and American Airlines, bed and breakfast accommodation in four-star hotels and paradors, transfers and sightseeing with local English-speaking guides. Rough Guides' Costa Rica guide (pound;13.99) and Costa Rica and Panama map (Pounds 5.99) are both excellent (www.roughguides.com