An object or place that's sunken is below the level of what's normal. A ship might sink and stay at the bottom.
When we talk about something being sunken, it usually means it's lower than it used to be or than its surroundings. For example, a room might have a sunken area for sitting on the floor, which is a low spot in comparison to the rest of the space. A lake can be a sunken valley because it's naturally lower than the land around it. People might use the word sunken when talking about old buildings or ruins too – like an archaeological site where some parts are below ground level and others are above.
(heading, physical) To move or be moved into something.
Caused, by natural or unnatural means, to be depressed (lower than the surrounding area) or submerged
Example: The sunken ship lay at a depth of 100 feet
