CONNECTING two LARGE water BODIES like seas and oceans is called strait.Example - Strait of Malacca.A lagoon is a water body separated from larger water bodies by a NATURAL barrier.A narrow strip of land that SEPARATES two water bodies and connects two larger landmasses is known as an isthmus.Example - Isthmus of Panama.A broad inlet or a small water body that is set off from a larger water body where the land curves inward is known as a bay.Example- Bay of Bengal.