SAN DIEGO (KGTV) -- Police say a paddle boarder attacked a man at Sunset Cliffs and broke his skull.

A place where Kevin Eslinger usually finds peace quickly became a nightmare.

Police say he got into an argument a man on a paddleboard on Tuesday. They say the man then cracked the paddle over Eslinger's head. The impact of the blow fractured his skull.

Pat Tope has been a swim coach with Eslinger at the Heartland Swim Association for nearly 30 years.

"He's the only one who's not afraid to give to his fellow mankind," said Tope. "He's pretty special to say the least."

The fractured skull put Eslinger in the hospital for two days.

"He was having difficulty with his speech, but since then his speech is slowly starting to return," said Tope. "So it's going to take some time for it to get back to normal."

Police say the man who hit him took off after the attack. No arrests have been made. The investigation is ongoing.