Gulf is a large area of water that is mostly surrounded by land with a narrow opening to a sea or ocean. Gulfs are usually deeper and more enclosed than bays. They can extend far into the land. Gulfs often have important coastal regions around them.

Gulfs are found along coastlines worldwide, such as the Persian Gulf and the Gulf of Mexico. They formed over long periods through Earth processes. Gulfs support marine life and are used by people for shipping and fishing. They are part of global water systems.