Isla Espirtu Santos, Baja
Credit: James Gritz / Getty Images

The warm, clear waters of the Gulf of California teem with dolphins, whales, reef fish and other marine life. A day trip to this uninhabited island, a UN Biosphere Reserve, offers all that plus playful young sea lions at the Los Islotes rookery. They circle, dive beneath, and come nose-to-nose with snorkelers, inviting you to follow. Try to keep up as you dive down through endless schools of silvery fish that part like smoke before you or swim through natural openings the rock. Bonus: Whale sharks inhabit this area from May and June. Baja Expeditions offers day trips from 8 AM to 4 PM including lunch, refreshments, guide and equipment.