The reef lies in Mexican waters offshore in the
Caribbean Sea, or about east of the city of
Chetumal. It is approximately long from north to south, and approximately wide at its widest point. It covers an area of . The atoll has three islands, with an aggregate land area of : • Cayo Norte (actually two separate islets) (0.9 km²) • Cayo Centro (5.6 km²) • Cayo Lobos (southernmost) (0.2 km²) The natural vegetation of the islands is largely
mangrove near the shore shading into open woodland more than from the shore. There is a crocodile reserve on the southernmost (and biggest) island. The crocodiles were once thought to be
American crocodiles, but it is now believed
they are a unique species. The islands (in common with many isolated tropical islands) are thickly populated with small crabs, which are tame and can be trodden on inadvertently by visitors. Some of the islands are inhabited by fishermen, who live in
stilt houses about offshore to circumvent local regulations forbidding private construction. ==Shipwrecks==