Neil Magnus hadn't been surfing for a couple of months due to work and life commitments but was determined to enjoy a dip and make the most of the beautiful weather.

His friend Chad Whatley was on the beach taking pics of the dolphins swimming in the surf near the Watonga Rocks about 11am on Saturday.

"There were about 15 of us in the vicinity of the dolphins, everybody else was near the flags," said Mr Magnus.

"I noticed the dolphins went past me at one stage and weren't being a playful as usual."

His mate went home to check through his photos when he came across one which shocked him.

"He came and showed me and we have been checking with some fishermen and others who know more about sharks than we do and they reckon it's a shark, and a pretty big one."

There are sharks in the ocean - that's where they live - so keep an eye out and swim between the flags.