It’s about 4am and I’ve been woken up by two things: by that tiresome, middle-aged need to pee at some point in the middle of the night, and by the disturbing sounds of some kind of animal scuttling up and down the wooden walls of the hut beside my bed.

Beyond those walls, the countless sounds, uncanny to a townie like me, of night in the rain forest, but’s it’s the little critter closest to me that has my attention. I’ve no idea what animal it is - a lizard, maybe? - and I’ve no idea whether it’s on the inside or out.

Not that it would make much difference, in any case, given that the gables of the palm-thatched roof of my ‘eco-hut’ are open - so anything that really wants to get inside the cabin, can do.

I’d rather stay just as I am, under the covers in my bed, surrounded by mosquito nets. But nature calls, quite insistently, and a few minutes later it’s me that’s doing the scuttling - blundering in the dark to the bathroom, where a fresh dilemma awaits me. Leave the lights off, and I’ve no idea just what I’m sharing the room with, but switch them on, and every moth in the rainforest will make a beeline for me.

Multimedia

• Colombia gallery by Jorge Monedero

Zipwiring in Colombia

Matthew Parris gets the ultimate adrenalin rush, skimming the treetops of Colombia's rainforest

• Paragliding on Tenerife

Hola, Howard Marks here, in Colombia

Howard Marks has spent a lifetime sampling Colombia's best exports. So time to pay a visit

Love in the time of Cartagena

The Colombian city inspired Gabriel Garcia Marquez’s Love in the Time of Cholera. Now it is the setting for the film of the book

• When Robert Elms met Gabriel Garíca Marquez

Related Links

• Colombia: from cocaine to green tourism

Multimedia

• Colombia gallery by Jorge Monedero

This is eco-tourism, Colombia-style. We were staying in one of the five cabins of the Posada Turistica San Rafael, near the stunning Tayrona National Park - part of a recent trip to the country we made using Cartagena, the fine old city which is one of Colombia’s key attractions to foreign tourists, as a launch pad for a slightly more adventurous trip.

Adventurous, in that we’d taken the speedboat ride (not so eco, maybe, but so much fun) from Cartagena to Agua Baru, the stunning boutique hotel with just three rooms on a peninsula overlooking the Rosario Islands, in a little bay where rich Colombians have built little getaways.

Adventurous, in that we found ourselves walking barefoot through the paths through the rainforest during a tropical thunderstorm, stepping over fallen palms, and stepping aside for mule trains driven by the local Indians (who very sensibly wear Wellington boots; or at least the men do, the women go barefoot).

So far, so adventurous, but for me, the real adventure, the moment that went beyond any kind of comfort zone, was that trip to the bathroom at the Posada Turistica San Rafael. And like all good adventures, it changed me a little, and made me bolder.

For by the next day, I was getting used to all the critters - so much so that after that rain-drenched hike through the Park and a skinny dip in the ocean, I was feeling ao acclimatised that I could sit on the veranda outside our cabin and feel almost at ease, despite the huge spider on the ceiling and a bat that kept whizzing past my nose.

Our journey had begun at Cartagena, arguably the gateway tourist experience in Colombia, as it is visited by daytrippers from the many visiting Caribbean cruise ships, also by literary types drawn by the cultural festival launched by the Hay Festival which takes place in the city every year (next year on the cusp of January and February, www.hayfestival.com/cartagena).

It is easy to see why they come. Founded by the Spanish in 1533, the old town of Cartagena contains within its dramatic walls some splendid Baroque churches, some fine palaces built by its merchants - many of whom grew rich on the slave trade, for which Cartagena was the most important hub in South America - and the occasional art deco gem, tucked away between the elegant houses built in the early nineteenth century in the elegant ‘Republican’ style.

If you enjoy your history, Cartagena is a fascinating place, even if the history here is grim, given that most of those wonderful buildings were built by the slaves, shipped in from Africa and sold in the Plaza de los Coches. There’s a monument dedicated to the city’s founder in the square; I found myself wishing there was a memorial to the slaves instead.

Times recommends

• New York hotels on sale in January
• Skomer Island, Wales: Britain's best job?
• Red Sea: the complete guide