Sea of Cortez — La Paz

Most La Paz diving is a day-boat routine: an early load-out at one of the marinas north of town, an hour or more running out through the San Lorenzo Channel, then two tanks with a surface interval anchored in the lee of Isla Espíritu Santo. Boats range from open pangas to small cabin cruisers, and crews build the day around conditions rather than a fixed plan, swapping the offshore seamount for a sheltered island wall when the wind gets up. The ferry wreck lying in the channel is a common fallback on those days, and shore entries near town make up a small part of the picture.

The terrain is desert rock rather than coral reef. The islands drop away in volcanic boulder fields and slabs seamed with sand channels, dressed in gorgonians and encrusting invertebrates instead of hard-coral gardens. Sites fall into three broad types: shallow broken rock around the islets, where the diving is easy and the animals come to you; steeper walls and swim-throughs along the exposed side of the island chain; and offshore pinnacles that top out well below the surface and ask for a descent straight into blue water.

The seamount dives work differently from reef diving. You drop on a line or go negative, hold position near the top of the structure and watch the blue, accepting that the schooling fish either show or they do not; hammerhead numbers there are widely reported to have thinned over recent decades. The sea lion dives are the opposite, shallow and social, with juveniles mouthing fins and spiralling through the group while adults patrol the edges. The rookery sits inside a national park, so operators work to permits and group limits, and in-water access can be restricted.

It suits intermediate divers comfortable with some current, an open boat ride, and water that swings from around 19°C late in winter to near 30°C at the end of summer, so exposure kit changes a lot across the year. Photographers who would rather shoot animal behaviour than coral get more out of it than anyone after wide, clear reef scenery. Many divers pair the diving with a drive down to the East Cape, or with island kayaking and the permit-controlled, snorkel-only whale shark trips run out of the same town.