Four people are lucky to be alive after two separate rescues off the Kaikoura coast today.

A surfer saved two teenage girls after waves threw them out of their inflatable dinghy about 11am.

Frantic family members watched from the beach as the two 14-year-olds were dragged out to sea as they attempted to swim to safety.

But then the surfer went to their rescue pulling them on to his board, Sergeant Barry Hanson of Kaikoura Police said.

The waves were so big they broke the surfboard but not before the trio were within reach of the shore.

St Johns paramedics treated the girls for minor injuries.

Both girls swallowed a lot of water and one was taken to hospital for treatment.

A man and a boy also escaped serious harm when they were swept into the sea off from their small yacht this morning.

The 59-year-old and 11-year-old were checking their craypots when a large wave tipped the boat.

Mr Hanson said the pair were not wearing lifejackets.

They clung to the vessel's paddles before being picked up by a passing boat after about one and half hours in the water.

Mr Hanson said they were treated by ambulance staff after suffering from the early stages of hypothermia.