Chetumal Bay is a semi-closed mesohaline estuary on the southern coast of the Yucatán Peninsula. It is located in northern Belize and southeastern Mexico.
The mouth of Chetumal Bay is directed southward and buffered by the large Belizean island of Ambergris Caye.
Corozal Bay is a smaller inland inlet, that extends to the southwest in the upper region of Chetumal Bay. It is named after the town of Corozal on it.
Chetumal is a major city on the bay, located in the Mexican state of Quintana Roo.
Chetumal Bay contains several blue holes, most notably the Taam Ja' Blue Hole. With a depth of at least 420m (1,380feet), it is the deepest known blue hole.