LAGOON

A stretch of salt water separated from the sea by a low sandbank or coral reef.

Sea birds, small hazel coloured crabs, butterflies, a fish that darts and puckers up among the rushes.

Half sea, half earth, half salt water, half sweet and a strange jumble of living forms (including humans, rarely absent on the terraqueous globe).

lagoon [ləˈɡuːn]; lagune [lagyn]; laguna [la·gù·na]; lagune [laɡuːnə] 

from Latin lacuna