Six-day return treks to the ruins of La Ciudad Perdida are very popular. Guides can arrange transport, food and accommodation (guides are essential because the area is an important marijuana and coca-growing region). The five to seven-day Nabusímake-Pico Colón Trek in the Sierra Nevada de Santa Marta is a great way to experience Colombia's mountains.
There is great snorkeling and diving off the Islas del Rosario, 30km (20mi) offshore from Cartagena, and off the the Isla Barú, the peninsula south of Cartagena. The waters around San Andrés and Providencia are ooh-aah pretty-fishy spots of choice delight.
Adventurous jungle tours of the Amazonian interior can be arranged in Leticia. Well-equipped guides are thick on the ground and tours of up to 10 days can be easily arranged. High-speed film - the jungle is often gloomy - and mosquito repellent are a must.
