Belize Barrier Reef in the context of "List of islands of Belize"

The Gulf (or Bay) of Honduras is a large inlet of the Caribbean Sea, indenting the coasts of Mexico, Belize, Guatemala, and Honduras. From north to south it runs from Cape Catoche to Caxinas Point.

The inner Gulf of Honduras is lined by the Belize Barrier Reef which forms the southern part of the 900 km (600 mile) long Mesoamerican Barrier Reef System, the second-largest coral reef system in the world. The Belize Barrier Reef includes a number of small islands, called cays, and collectively known as the Pelican Cays.

A cay (/kiː, keɪ/ KEE, KAY), also spelled caye or key, is a small, low-elevation, sandy island on the surface of a coral reef. Cays occur in tropical environments throughout the Pacific, Atlantic, and Indian oceans, including in the Caribbean and on the Great Barrier Reef and Belize Barrier Reef.

The Mesoamerican Barrier Reef System (MBRS), also popularly known as the Great Mayan Reef or Great Maya Reef, is a marine region that stretches over 1,126 kilometres (700 mi) along the coasts of four countries – Mexico, Belize, Guatemala, and Honduras – from Isla Contoy at the northern tip of the Yucatán Peninsula south to Belize, Guatemala and the Bay Islands of Honduras. It is the second-longest reef system in the world.

It includes various protected areas and parks including the Belize Barrier Reef, Arrecifes de Cozumel National Park, Hol Chan Marine Reserve (Belize), Sian Ka'an biosphere reserve, and the Cayos Cochinos Marine Park. Belize's coastline, including the Belize Barrier Reef, is home to approximately 30% of the Mesoamerican Barrier Reef System.

The Great Blue Hole is a large marine sinkhole off the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll 70 km (43 mi) from the mainland and Belize City. The hole is circular in shape, 318 m (1,043 ft) across and 124 m (407 ft) deep. It has a surface area of 70,650 square metres (760,500 sq ft). It was formed during several phases of the Quaternary glaciation when sea levels were much lower. Analysis of stalactites found in the Great Blue Hole shows that formation took place 153,000, 66,000, 60,000, and 15,000 years ago. As the ocean began to rise again, the cave was flooded. The Great Blue Hole is a part of the larger Belize Barrier Reef Reserve System, a UNESCO World Heritage Site.