to propel oneself through water by moving the arms and legs or (in fish) the tail and fins.
(or by slowly, steadily pressing on the gas pedal while throwing your considerable weight from side to side in your chair to influence the angle of the car)
This is a picture of the actual flood we drove through. I can only thank the goddess that my travel companion was so calm, that Scully was my own personal fear/panic/tornado hotline, and that my body inspired my car to hold on to the earth, enough to keep the car from being swept away in the rush of water!
Apologies to the woman on the right for the unflattering picture but it an excellent demonstration of what kind of water we're talking about. (Just in case anyone were to accuse me of employing hyperbole.)