A crocodile has forced an emergency evacuation of the water at the World Surf League event in Costa Rica.

Aussie Ethan Ewing was competing in the first heat of round five when one of his opponents, Brazilian Tales Rodrigues, spotted the crocodile.

The lifeguards patrolling the waters on jetskis sprang into action and circled around Rodrigues to ward off the crocodile as the surfers made their way back to shore.

Rodrigues says he was shaken after the event, which he called “terrifying”.

“I ended my wave and was paddling back strongly when I saw the turbulence in the water,” Rodrigues said.

“It was about the size of my surfboard.

“I have no words to describe what I’m feeling right now, it was truly terrifying.”

No-one was physically harmed, and WSL officials have congratulated Rodrigues for alerting officials.

Croc incident follows Mick Fanning’s run-in with a shark. Photo: Getty

“Rodrigues’ quick actions to make the water safety aware was amazing and the water safety team’s rapid response was truly commendable,” WSL North America tour manager Brian Robbins said.

“The safety of our athletes is of the highest priority for the WSL and the decision was made to call the contest off for the day immediately.”

In July last year, Australian surfer Mick Fanning famously punched a shark in the nose to fight it off as it tried to grab him during an event in South Africa.