A man has died after the boat he was sailing in capsized off the coast of Hokitika in the South Island today.

The vessel tipped over in the swell at the mouth of the Hokitika River, off Gibson Quay, shortly after 1pm.

"Another man who was in the boat when it capsized made it safely to shore, where he was treated for shock by paramedics," a police spokesman said.

"Both were wearing life-jackets when the boat flipped".

The matter has been referred to the coroner.