Why do scuba divers fall backwards off of the boat?
Because if they fell forward, they'd still be on the boat.
Scuba Diver's Backward Fall
Explanation
Explain Bear
Alright, listen up, you knucklehead. Here's the deal: a scuba diver's gotta get in the water somehow, right? If they fall forward, they ain't goin' anywhere 'cause they're still on the freakin' boat. Fallin' backward gets 'em in the water. Duh!