John Goldfinch, 61, was fishing for mackerel on the beach at Budleigh Salterton, Devon, with mates Colin and Alan Ashley when he felt a huge bite.
The thrilled lifelong angler had to fight to reel in the catch as he looked forward to netting a massive fish.
But his excitement turned to shock when his hook surfaced about 15 metres offshore to reveal the hapless frogman.
To add insult to injury the struggling diver had been hooked between his legs.
Mr Goldfinch, of Exmouth, said: "My mates were falling about laughing. I said 'sorry mate, I didn't see you there' and he just said it was very murky down there.
"The funniest thing was that his girlfriend then surfaced, helped him remove my tackle from his tackle and nonchalantly handed the hook back to me and apologized.
That's not how you put the worm on the hook, son.
I am not your rolling wheels, I am the highway
I am not your carpet ride I am the sky
I am not your blowing wind, I am the lightning
I am not your autumn moon, I am the night