Swimming with Whale Sharks

Isla Mujeres, a short boat ride from Cancun, Mexico, hosts the richest whale shark gathering on the planet each summer. Snorkelers slip into blue water beside spotted giants the length of a bus, feeding with mouths wide on plankton. On peak days hundreds of sharks crowd the surface, visible as dark shapes from the boat before you ever get in. Ningaloo Reef in Australia and La Paz Bay in Baja California offer the same encounter in other months, while Isla Mujeres peaks July and August within its June to September season.