आखात म्हणजे तीन बाजूंना जमिनीने वेढलेली आणि केवळ एकाच बाजूने पाणी असलेली जलीय रचना होय. काहीवेळा मोठा विस्तार असलेल्या आखातास उपसागर असेही म्हटले जाते; मात्र कितपत विस्ताराच्या जलीय रचनेस आखात म्हणावे किंवा उपसागर म्हणावे, याबद्दल निश्चित मोजमाप नाही.

A gulf is a large inlet from the ocean into the landmass, typically with a narrower opening than a bay, but that is not observable in all geographic areas so named. The term gulf was traditionally used for large highly indented navigable bodies of salt water that are enclosed by the coastline. Many gulfs are major shipping areas, such as the Persian Gulf, Gulf of Mexico, Gulf of Finland, and Gulf of Aden.