A rescue operation for passengers of a boat that reportedly capsized off a Kaikoura bay is underway

A police spokesperson says they're responding to the incident off Goose Bay and the South Bay slipway is closed, while this happens.

Two helicopters have also been dispatched to help.

An image on social media shows a number of people on top of the upturned boat, awaiting rescue.

Maritime New Zealand is sending an investigator to Kaikoura to determine the cause of the incident.