Dan Carlin's wife told him to smile for a picture on their boat as he held up one of the yellowtail fish they had caught that day off San Diego. Then a sea lion leaped out of the water, bit into his hand and yanked him overboard.

The animal, weighing hundreds of pounds, smashed the 62-year-old accountant against the boat's side and sent his legs flying into the air like a rag doll's before it dragged him some 20 feet (six metres) underwater, Carlin said on Wednesday, more than three weeks into his recovery after the incident on 5 April.

"After 15 seconds, I thought I was going to die," Carlin said. "I continued to struggle, but thought this is the way I was going to die. It was unbelievable to me."

Then, as quickly as the attack happened, Carlin was released. He swam towards the surface as the sea lion bit his foot, puncturing a bone.

He managed to make his way back to his boat. He and his wife, Trish, moved it closer to land while his hand gushed blood and he struggled to breathe because of his battered chest. At one point, Carlin said, he lost his vision.

Carlin spent two days in the hospital. The gash on his hand required 20 stitches.