With hundreds of trails and countless rivers and waterfalls, the Parc National de la Guadeloupe on Basse-Terre is the main draw for hikers. Some of the trails should be attempted only with an experienced guide. All tend to be muddy, so wear a good pair of boots. Know that even the young and fit can find these outings arduous; the unfit may find them painful. Start off slowly, with a shorter hike, and then go for the gusto. All water sports—even canoeing and kayaking—are forbidden in the center of the park. Scientists are studying the impact of these activities on the park's ecosystem.

Les Heures Saines. Originally a diving operation, Les Heures Saines has come ashore to offer freshwater canyoning in a river outside the national park as well as hikes to La Randonnée and the volcano. There are three different canyoning circuits, including one called the Trail of the Three Waterfalls that lasts six to seven hours. On the Bivouac trip you spend 24 reality-show-like hours in the forest. For many of these excursions, you have to wait for a group to be assembled. Book as far in advance as you can. Le Rocher de Malendure, Plage de Malendure, Bouillante, Basse-Terre, 97125. 0590/98–86–63; www.heures-saines.gp. From €45.

Vert Intense. Vert Intense organizes hikes in the national park and to the volcano. You move from steaming hot springs to an icy waterfall in the same hike. Guides are patient and safety-conscious, and can bring you to heights that you never thought you could reach, including the top of Le Soufrière. The volcano hike, the cheapest excursion, must be booked four days in advance. When you are under the fumaroles you can smell the sulfur (like rotten eggs) and you and your clothes will smell like sulfur until you take a shower. A mixed-adventure package spanning three days costs considerably more. The two-day bivouac and other adventures can be extreme, so before you decide to play Indiana Jones, know what is expected. The French-speaking guides, who also know some English and Spanish, can take you to other tropical forests and rivers for canyoning (climbing and scrambling on outcrops, usually along and above the water). If you are just one or two people, the company can team you up with a group. Vert Intense now has a guesthouse, les Bananes Vertes (The Green Bananas), where you can combine a stay with trekking and other activities. Rte. de la Soufrière, St-Claude, Basse-Terre, 97100. 0590/99–34–73; 0690/55–40–47; www.vert-intense.com. From €30.