Isla Bastimentos' geology is similar to Isla Colon's, that is a rugged interior, mangroves on the sheltered west side and sandy beaches including the 6 km Playa Larga beach on its east side.
Playa Larga, which is part of the National Marine Park, is an important sea-turtle nesting area, attracting four species of endangered turtles from about April or May through September. You will see the sea turtles if you camp out or make a night hike from one of the island's hotels.
However, the surf at those beaches makes swimming unsafe.You can surf the beaches and reefs of Bastimentos National Marine Park but for this location, experience is a pre-requisite, and is only really suitable for advanced surfers. Three unnamed breaks produce long, hollow tubes. Two of the three waves are reef points, and sandbars at a creek mouth form the third. Currents can be strong and the waves can have faces of over 12 feet.