Eleven-time world champion Kelly Slater says Conner Coffin’s surf with dolphins at the Margaret River Pro on Saturday was one of the “coolest things” he’s ever seen.

Slater, Owen Wright, Julian Wilson and John John Florence were among the big names to win their round-three heats in the six-to-eight foot conditions at The Box.

But it was Coffin’s barrelling wave during his heat win over Jesse Mendes that stole the show on a magical day of competition.

The duo had dolphins swimming all around them at various points of their heat.

And when Coffin launched himself onto a barrelling wave, a pod of at least five dolphins joined him for the ride.

“It was insane,” Slater said. “There were like six dolphins in the lip. I thought one was going to get pitched.

That was one of the coolest things I’ve ever seen in my life.”

The ride with dolphins helped Coffin outscore Mendes 12.33 to 9.20.

“I just got that wave, and then I looked up and there’s a pod of dolphins right by me and a perfect blue set coming,” Coffin reflected.

“I thought, ‘Oh my god this is insane’. I was really excited.”

Two-time world champion and former Margaret River champion Florence crashed out on his first wave.

But he recovered with a series of solid barrels to post a two-wave score of 11.83, edging past Australian Jack Freestone (9.16).

“I wouldn’t say it was one of my best heats, but it’s always nice to make it through the close ones,” Florence said.

Slater also copped it from the waves during his heat, but pulled off some smooth rides to beat Willian Cardoso 10.06-7.34.

Australian wildcard Jack Robinson produced the best performance of the day, with the Margaret River local’s two-wave tally of 18.57 smoking Filipe Toledo (6.73).

But the news wasn’t as good for 2018 world champion Gabriel Medina, who was pipped by Caio Ibelli in their third-round heat.

Medina, who last year expressed fears about re-entering the WA water following two nearby shark attacks, lost 13.67-13.23.

Brazilian Italo Ferreira produced a remarkable tube ride during his dominant heat win over Soli Bailey earlier in the morning.

Italian Leonardo Fioravanti was forced to pull out of his third-round heat after dislocating his shoulder while free surfing on Saturday morning, handing Jordy Smith a pass into the fourth round.

And Brazilian Jadson Andre needed help from a jet ski to escape the danger zone after wiping out head-first onto the reef section during his loss to Wilson.

Andre was left nursing a sore back and had to be carried after reaching the shore.

-AAP