Grampin

Grampin dives as a series of rooms rather than a wall. Sandy channels run between coral formations tall enough to block the view sideways, so you follow the corridor, pass under an arch, and come out somewhere slightly different. A gentle current carries you through it and keeps schooling fish stacked over the structure.

Four kinds of coral grow along the same stretch, which is unusual on this coast after 2005: brain coral in heads along the corridor walls, staghorn in branching thickets, sea fans standing into the flow, and fire coral wherever there is a hard surface. Large sponges fill the gaps. Lobsters back into the ledges and nurse sharks lie under the bigger overhangs.

Depth runs mid teens with the deepest points around seventeen metres.

The name is the short version of what the site is. Grampin is Mexican Spanish for an anchor, and the reef makes that shape, which is a rare instance on this coast of a dive site named for its own topography rather than for a boat, a saint or a hotel.

Underwater the distinction is the enclosure. Most of the Punta Cancun line is an edge you drift along; this stretch is one you drift through, with coral above shoulder height on both sides for much of the dive.

Fire coral is the thing to watch. In an open drift you can keep a metre off everything without thinking about it. In a corridor with walls on both sides that takes attention, and fire coral stings through a thin suit.

The arches are short and lit, but they are still overhead. Keep an exit in view, and if you are diving in a large group, let the queue clear rather than joining a bottleneck inside one.