Surf Life Saving Bay of Plenty has confirmed a man snorkelling on the Pilot Bay side of Mauao was lunged at by a two metre Mako shark on Thursday afternoon.

The incident sparked the closure of Mount Maunganui Main Beach at about 2.30pm.

Lifeguards worked to clear Mount Maunganui Main Beach after a shark was sighted further around the shore toward Pilot Bay.

Surf Life Saving Bay of Plenty club development officer Michael Lord says the man was using a snorkel to collect shellfish at Mauao's south-western corner when the shark 'lunged” at him.

Michael says the man managed to escape from the water unharmed, but immediately fled to the Mount Maunganui Surf Club to raise the alarm.

'The shark came really close the first time and the next it came really close and lunged at him,” says Michael.

'The guy pulled out his knife and tried to stab it.”

Lifeguards believe the man was using the knife to remove shellfish from the rocks.

The report of the shark led to the closing of the beach.

'If there are any shark sightings that are thought to be big sharks we close the beach until we are confident that we haven't seen it near the beach for a couple of hours.”

Mount Maunganui Main Beach was closed to swimmers until lifeguards finished their patrols at 6pm on Thursday.

Michael says the beach will reopen on Friday but is warning swimmers to be cautious.

'The shark has not been spotted around Mount Main Beach side so as far as we're concerned it's still safe and the lifeguards will keep an eye out but I wouldn't say go swimming right out.”