A teenager who was bitten by a shark while spearfishing on the NSW south coast recorded footage of the terrifying moment the animal, believed to be a bronze whaler, latched on to his hand.

Sam Smith, 17, admitted he got too close to the shark when it suddenly swam towards him off Bannister Head in Mollymook on Friday morning.

The Year 12 student was wearing a GoPro camera at the time, and the footage, obtained by Channel 7, shows the shark biting into his right hand and spear gun as he tries to fend it off with his left hand.

The attack lasted just a second, but left Sam with deep gashes to his hand, severed nerves and tendons, and bone damage.