The Sea of Cortez is a warm, subtropical diving region between Baja California and mainland Mexico, known for clear-water itineraries, productive reefs, and seasonal wildlife movements. Divers come here for sea lions, rays, pelagics, and occasional hammerheads, with boat trips and liveaboards reaching the most interesting sites. It is a flexible destination rather than a single-profile dive, so season and site choice matter as much as depth. Late summer and autumn usually give the best mix of warm water, visibility, and marine life.