I think your thinking of a pond or a lake
a bay
a bay
That would be called a bay.
sea
Greece is a large peninsula with a lot of smaller islands and it is also surrounded by many large mountains.
A large area of land which is completely surrounded by water is a continent. A small area of land which is completely surrounded by water is an island.
If it's surrounded on all sides then it's called an island; if it is partly surrounded then it's called a peninsula.
No continents are considered islands. Continents are large landmasses that are connected to each other and are typically surrounded by oceans. Islands are smaller landmasses that are completely surrounded by water.
a plateu
An island.an island e.g. U.K, Greenland, Ireland, Australia, Japan
lithosphere Islands and continents are usually found in areas that have been surrounded by a large mass of water.
A bay is a body of water that is partly enclosed by land (and is usually smaller than a gulf).