The Parque Nacional Arrecifes de Xcalak (Xcalak Reef National Park) was established at the end of 2003, affording protection to the coastal ecosystem as well as Xcalak [1]’s nascent tourist economy. The park spans nearly 18,000 hectares (44,479 acres), from the Belize [2] border to well north of town, and includes the reef—and everything else down to 100 meters (328 feet)—as well as the shoreline and numerous inland lagoons.
The main coral reef lies just 90–180 meters (100–200 yards) from shore, and the water is less than 1.5 meters (5 feet) deep almost the whole way out. Many snorkelers prefer the coral heads even closer to shore, which have plenty to see and less swell than the main reef. The shallow waters keep boat traffic to a minimum, and anglers are good about steering clear of snorkelers (you should still stay alert at all times, however).
Divers and snorkelers [3] also can explore the reef at 20 or so official sites and many more unofficial ones. Most are a short distance from town, and shops typically return to port between tanks. La Poza is one of the more distinctive dives, drifting through a trench where hundreds, sometimes thousands, of tarpon congregate, varying in size from one-meter (3-foot) “juveniles” to two-meter (7-foot) behemoths.
A fee of US$5 per day technically applies to all divers and snorkelers (and kayakers and anglers) in the Parque Nacional Arrecifes de Xcalak; dive shops typically add it to their rates, while most hotels have a stack of wristband permits to sell to guests who want to snorkel right from shore.
Links:
[1] http://www.moon.com/destinations/cancun-the-yucatan/cancun-cozumel-and-the-riviera-maya/tulum-and-southern-quintana-roo/la-costa-maya/xcalak
[2] http://www.moon.com/destinations/belize
[3] http://www.moon.com/destinations/cancun-the-yucatan/cancun-cozumel-and-the-riviera-maya/tulum-and-southern-quintana-roo/la-costa-maya/recreation-0