Dozens of beach-goers had to leave the water at Papamoa Beach on Monday when a shark, believed to be a bronze whaler or a thresher, came within about 10 metres of the shoreline.
Surf lifeguard Shaun Smith says a lot of sharks swim in the area at this time of year, but this shark came too close for it to be safe for swimmers to stay in the water.
He says the shark came close to a couple of swimmers but when they splashed it, it swam back out into the ocean.
Mr Smith says the shark might have been attracted to the beach by chunks of beef that had washed ashore from the Rena.
The Rena remains firmly grounded on the Astrolabe reef, off Tauranga, where it has been stuck since 5 October last year and by last week 89 of the vessel's 1368 containers had washed overboard.
