Estuary

From Environmental Technology

An estuary has very little wave action, so it provides a calm refuge from the open sea. Some of the animals, such as flounder, eels, and striped bass are just visitors to the estuary. Small fishes such as stickleback and mummichogs, mud snails, and oysters may spend their entire lives there.

[edit] reference

http://www.gma.org/katahdin/estuary.html