Sensible optionLightning Bolt, $59 
Splurge option
Onia, $145 
Why dad needs it: No matter how much we love our dads, they'll always find a way to embarrass the shit out of us. And there's no time where this has more potential than at the beach or the pool. Your pops may still be hanging on to his favorite pair of trunks, but as summer gets into full swing, this is one item that definitely needs an upgrade. Cop him a new pair and burn the old ones.