The main draw at Islas del Rosario is underwater. Snorkelling and scuba diving on the coral reefs are the primary activities, with visibility often exceeding 20 metres on clear days. The park has 28 known diving sites at various depths. Boat tours typically stop at several reef sites and include lunch on one of the islands. On the surface, the beaches on the smaller islands are quiet and beautiful — the kind that feel genuinely remote despite the short boat ride from Cartagena.
The aquarium and oceanarium on Isla Rosario are worth visiting if you're travelling with children. Isla Grande is the largest island and the best base for those who want to spend the night.