Chetumal Bay is a large bay in northern Belize and eastern Mexico in the south of the Yucatán Peninsula. On the bay is the major city of Chetumal, in the Mexican state of Quintana Roo. The mouth of the bay is redirected southward and buffered by a large Belizean island named Ambergris Caye. A smaller inlet known as the Corozal Bay, named after the town of Corozal, extends to the southwest. The bay is a part of the Caribbean Sea.