Tofo Bay holds one of the densest concentrations of whale sharks anywhere on earth. From October to March, seasonal plankton blooms draw these enormous fish — the largest in the ocean, reaching 12 metres and more — to the surface, where they feed with their vast mouths open. Several established dive centres run daily excursions to snorkel or dive alongside them.
No diving experience is required for the snorkelling trips. A guide drops you into the water alongside the shark, which moves at its own patient pace and is entirely indifferent to the humans beside it. The experience — swimming next to an animal the size of a bus, filtering plankton from the water, utterly uninterested in you — is difficult to describe. Whale sharks are present year-round but peak in numbers between November and February. Book at least a day ahead in high season.