What is a narrow area of water that goes into the land from a sea?

A narrow area of water that extends into the land from a sea is known as a "fjord" if it is characterized by steep cliffs and is typically formed by glacial activity. Alternatively, it can also be referred to as a "bay" or "inlet," which are generally more open and less steep, allowing for easier access to the land. These features can vary significantly in size and shape, depending on the geographical context.