MUSA (Underwater Museum of Art)

You drop onto white sand at eight metres and the figures are already visible before you reach them. They stand in groups rather than in a line, so the dive works as a slow wander rather than a route, and at this depth a tank lasts long enough to go back for a second look at anything.

The largest installation is a crowd of several hundred people facing in different directions, and it is worth swimming out and turning back towards it to see the whole thing at once. Elsewhere there are smaller pieces on their own, a car, a house. Coral has taken hold on most surfaces and the figures are no longer clean cement, which changes what you are looking at: faces softened by sponge and fire coral, outstretched arms carrying growth. Grunts hang in the shade underneath, stingrays sit out on the sand between the groups, and turtles pass through on their way to the seagrass.

Hurricane Wilma crossed this coast in October 2005 and destroyed a large share of the natural reef around Isla Mujeres and Cancun. What survived then had to carry the same number of divers as before. The marine park and the Cancun Nautical Association commissioned an artificial alternative, and installation began in 2009 with the British sculptor Jason deCaires Taylor.

The figures went down on bare sand, downstream of the natural reef, so that coral spawn would drift across them and settle. The material was chosen for the same reason: pH neutral cement rather than anything that would leach. The largest installation was cast from more than ninety fishermen and women from Puerto Morelos, a fishing town further down the same coast 1.

The marine park and the Cancun Nautical Association commissioned these figures after Hurricane Wilma tore through the reefs in 2005, and gave them two jobs at once: pull divers off what coral survived, and give new coral somewhere to grow. The material is pH neutral cement, and the sculptures were placed downstream of the natural reef so that spawn drifts onto them and settles. The artist reports more than two thousand juvenile corals now growing on the collection.

The part that rarely makes it into English coverage is who the figures are. The main installation was cast from more than ninety fishermen and women from Puerto Morelos, further down the coast. They are not models hired for the job. They are the fishing families of a town whose living depends on the reef, standing on the seabed, being slowly turned into reef themselves.

There are two galleries and only one of them is a dive. Salon Manchones, at eight metres, is where divers go. Salon Nizuc on the Cancun side sits at four metres and is snorkelling only, which catches people out when they book what looks like the same thing from a Cancun hotel. If a trip is sold as the Cancun underwater museum, ask which gallery.

Buoyancy matters more here than anywhere else on the island, and not for your own safety. The coral growing on the figures is the entire reason the site exists, and it breaks. Sort your trim on the sand before you go near anything.

It is busy. Snorkel boats work the same water, so keep a line or an SMB for the ascent. And the site is genuinely shallow, which makes it a good early dive and a poor one to save for last.