The waters off Donsol are where you have one of the best chances to swim alongside the largest fish in the sea. Known locally as Butanding, whale sharks converge here in phenomenally large numbers from October till June. With a little bit of luck, you might even see up to 15 whale sharks in a day! These gentle giants can measure up to 12 m, but are surprisingly friendly and calm, often interacting with the snorkelers they encounter. Touching the whale sharks is a strict "no" though, as it removes the protective layer of mucus preventing infection. You're not allowed to dive to limit the human interference but beware of lethal snorkelers indiscriminately kicking as though their lives depend on seeing the large pelagic. If jumping from a moving boat and swimming after a whale shark isn't your thing, Donsol offers a variety of other activities like firefly watching, kayaking and scuba diving with manta rays.