There was a worrying moment for surf fans and Kolohe Andino at the Hurley Pro when what appeared to be a shark hoved into view during his second round heat at Lower Trestles.
In front of a packed crowd of thousands at the ASP World Tour event, which was won by surf legend Kelly Slater, a large, grey silhouette was clearly visible beneath the surf as Andino caught a wave (pictured above).
And there was only one question on the minds of the onlooking spectators, fellow competitors and judges – "was that a shark or a dolphin!?"
There were arguments for both cases, with those pushing the shark argument pointing to the fact that the dorsal fin appeared too straight to be a dolphin, plus it was swimming alone, which is generally more typical of a shark.
Conversely, those arguing that it was a dolphin pointed out a sighting of an entire pod of them at the nearby San Onofre State Park earlier that morning. Those of that viewpoint also suggested that the tail appeared to be more horizontal – a likely sign of a dolphin.
Historically, dolphins are the more regular visitors to Trestles and have been riding the surf there for centuries, but it's not unusual to see white sharks in the area too.
There will never be a 100 percent difinitive answer of course, but experts who have studied the image believe that it was a bottlenose dolphin based on the presence of a single falcate dorsal fin.