A surfer says he's "really, really lucky" to have punched and kicked his way out of the jaws of a shark, with one witness saying it was like Mick Fanning's miraculous escape "but worse".

Marcel Brundler, 37, has just a souvenir scratch on his back after the three-metre shark grabbed him while surfing at Cathedral Rock near Lorne, south-west of Melbourne, on Tuesday.

"At first I didn't think anything of it, we have lots of dolphins in the water here, but then I realised it was big, much bigger," Mr Brundler said.

"I'm no expert but this was at least three metres long."