A man has died after being pulled unconscious from waters near the Kiama Blowhole on the NSW south coast.

Key points: Authorities used a helicopter to help remove the man from the surf

Authorities used a helicopter to help remove the man from the surf The ABC understands the man was snorkelling with a group of people

The ABC understands the man was snorkelling with a group of people They became caught in an undercurrent near the blowhole

He was snorkelling with four others and became separated from the group and caught on rocks near the base of the popular tourist attraction.

The ABC understands the 33-year-old had a heart attack and surf lifesavers attempted to pull him from the water, but were unable to.

He was spotted in the water near the blowhole about 12.30pm.

They were caught in an undercurrent and the man became separated from the group.

An emergency helicopter was called to the scene and a paramedic was winched down into the water.

Acting NSW Ambulance Inspector Robert Kembrey said the man was then flown to the Kiama boat harbour helipad where more paramedics were waiting to treat him,

"The crew from the helicopter worked on the man for half-an-hour, but unfortunately they were unable to resuscitate him," he said.

Authorities say the man may have panicked after thinking he was being sucked into the blowhole. ( ABC News )

The other divers were not seriously injured, but one was taken to Shellharbour Hospital as a precaution.

Senior lifeguard Craig Bowley was the first responder to the rescue, and said reversing the jet ski into the cave was a challenge.

"I didn't want to put the ski on the rocks, and the two gentlemen that were holding him up struggled to get him on the mat, but we eventually got him out and the helicopter winched him up," Mr Bowley said.

Kiama Council head lifeguard Andy Mole said his team responded immediately and had the jet ski onsite within a minute.

He said it was believed the man was snorkelling when he likely thought he was being sucked into the blowhole and panicked.

"The lifeguard on the ski did an amazing job and did CPR on the sled itself until the ambulance arrived," Mr Mole said.

"If you're inexperienced ... there's a feeling you may get sucked into the blowhole and get panicked."