Do the backstroke or breaststroke

SWIM

Think of a way to move through water that doesn’t involve walking or floating—it’s what fish do naturally.

This clue describes two common swimming styles—the backstroke and breaststroke—to hint at the general action they belong to. Since both are types of swimming, the answer is simply "SWIM," the verb that covers all strokes. There’s no wordplay here; it’s a straightforward definition pointing to the broader activity.