* Sea: A large body of salt water that is partially enclosed by land.

* Gulf: A large body of water that is partly enclosed by land, often an extension of an ocean.

* Bay: A body of water partially enclosed by land, usually smaller than a gulf.

* Lagoon: A shallow body of water separated from a larger body of water by a barrier island or reef.

* Estuary: A body of water where freshwater from a river meets saltwater from the sea, creating a unique ecosystem.

Can you provide more context?

For example:

* Is the water saltwater or freshwater?

* What is the purpose of the protection?

* Is it a natural formation or man-made?

This will help me narrow down the possibilities and give you a more accurate answer.