A more thorough explanation:

A Great Pond is a body of water that is larger than ten acres and is subject to public ownership in Maine and Massachusetts. It is also known as a public pond.

For example, if a lake in Maine is larger than ten acres, it is considered a Great Pond and is owned by the public. This means that anyone can use the lake for recreational activities such as fishing, boating, and swimming.

The Great Pond designation ensures that these bodies of water are protected and accessible to the public.