I just thought about what I'd do if I was on a sinking ship and of course breathing was the first thing that came into my consideration.
Now imagine the ship's front going up and the room you are in being filled with water. An upper edge of the room (where 2 side-walls and the ceiling meet) will be - at one point - the only one containing air (as the rest of it is filled with water). I could swim there and grab some air before trying to escape. But regarding the fact that water doesn't compress very well this will get harder the less volume is taken by the air.
When I think about 100l of air at the described edge of the room I suppose this won't affect breathing too much as I guess there is enough space to compensate the pressure. But let's say there is only 2 liters of air surrounded by said water, do you have a chance? Your lungs won't be able to push the air that much that the water level somewhere else at the ship will rise (maybe at the edge of the room next to you) right?