Boat's bottom

KEEL

This underwater ridge helps stabilize a ship and prevents it from drifting sideways in strong winds.

The word "keel" refers to the central structural beam running along the bottom of a boat, giving it stability. In this clue, "bottom" is used literally—it’s not a trick or pun, just a straightforward definition. If you picture a ship’s hull, the keel is the backbone that sits lowest in the water. Crossword solvers often see nautical terms like this, so recognizing basic boat parts helps.