Who is it that rows quickly with four oars but never comes out from under his own roof?

Why this works

This riddle cleverly plays with the imagery of a turtle and its shell. The "four oars" refer to the turtle's four limbs, which it uses to paddle through the water, while "never comes out from under his own roof" highlights the fact that a turtle carries its shell on its back and can retreat into it for protection. So, the riddle describes the turtle's unique way of moving and its characteristic of always having its shell as a form of shelter, creating a fun juxtaposition between speed and safety.