Paraiso Bajo

You roll in across from the mouth of La Caleta marina and the water starts moving you north, towards town and towards the ships. Two or three low coral ridges lie parallel to the beach, a couple of hundred metres off it, with lanes of sand in between. Coral heads three to six metres tall rise from the sand along them, hung with sponges and anemones, and the schooling fish sit around them: grunts, snappers, sergeant majors and queen angelfish. Nothing here is deep. The reef top is shallow enough to keep the whole dive inside fifteen metres, and most boats work it between nine and twelve.

Then the guide turns away from the reef, towards the beach, and swims out over open sand. That looks like a mistake and it is the point of the dive: the animals people came for are in the sand. Scorpionfish sit in it without moving. Peacock flounder go up in front of you and settle again. Southern stingrays lie in the shallows inshore of the ridges, and somewhere in that ground, if the guide knows which patch to check, there is a seahorse. That stretch of sand is the part of the dive people describe afterwards.

The ground under all of it is a staircase cut into the shelf. A shallow terrace runs out from the beach to about four metres, a step drops from four to ten, and it is that step, between ten and fifty metres offshore, that carries the ribbon of small reefs you are diving. A second terrace holds a steady ten metres further out, and a final step falls to fifteen.

The thing to keep track of is where you are going. You are drifting north and the Puerta Maya cruise berths are north, under four hundred metres from the reef. On a fast day that distance closes quickly, which is why the ascent starts well before the reef runs out.

The national park starts here. The park's northern corner sits on this reef's north tip, which makes Paraiso the line: the water a few hundred metres north of your entry is unprotected and fished, and everything from here south to the tip of the island is inside the park, with fishing prohibited along the whole of it1. Cozumel's protection has an edge and you can dive it.

The other edge is industrial. The Puerta Maya cruise berths sit less than four hundred metres north of the reef, and that proximity is why the first scientific recordings of the splendid toadfish were made here, on a recorder left on this reef for fifty days2. Cruise ship and small motorboat traffic raised sound levels for up to fifteen hours a day in the same frequency band the toadfish calls in, and the calls themselves increase at night. Whether that noise masks the calls is an open question2. An endangered fish that is effectively Cozumel's own lives under ledges four hundred metres from where the ships tie up.

The third thing is the traffic in the water. This is the most heavily dived reef in the park and has been for as long as the park has existed1. It is closest to town, it is the shallowest, and it is the easiest thing to sell. Almost nobody's trip to Cozumel is about Paraiso and almost everybody's trip contains it. What that costs the reef is visible in the coral; what it costs the diver is company.

There is nothing romantic in the name. The reef is said to be named after Rancho Paraiso, the property that stood behind the beach.

Two pieces of harder history sit on the same stretch of water. La Caleta, the small marina immediately south of the reef beside the Presidente hotel, has worked as a mooring, fuelling and repair basin since long before the dive boats used it as a starting point, which is part of why the channel inshore of the reef is busy. And in October 2005 Hurricane Wilma destroyed the Puerta Maya cruise pier at the northern end of the drift. The dredging for its remains was still under way in 2009, when a group diving the reef was carried into the working area by a change in the current.

Divers who knew this shoreline before Wilma describe the nearshore water as a richer place then, with more coral and more fish close in. What they remember is a coastline that has since had a cruise terminal rebuilt on it.

Most people meet this reef on somebody else's plan. It is the second tank of a morning boat that spent its first on a southern wall, or the site where a resort course or a certification dive happens, so the profile is usually settled before you turn up. Say what you want out of it. Asking for time over the sand instead of a lap of the coral changes the dive more than anything else you can request here.

The guide will check your buoyancy before you go in, and that is not a formality on this stretch of reef. The park's rules for this zone are the only ones on the island that make scuba conditional on demonstrating buoyancy control, which is what a shallow, busy, much-collided-with reef has earned1. Fin tips above the ridge tops, no settling on the coral to hold position for a photograph.

Do not feed anything. Feeding, chasing or disturbing marine animals is prohibited across the park, in their refuges most of all, and that includes the morays here, whatever a shop's own page might invite you to bring along in your pocket.

The park rests its reefs in rotation, two months at a time, and this one is on the list. Nobody publishes a calendar for the year, so ask your dive shop which reefs are resting for your dates. Do that before you build a day around one particular reef.