Six people have been taken to hospital after a collision between a power boat and a trailer yacht at Waikawa Bay, near Picton, this afternoon.

The alarm was raised at 12.53pm.

Two ambulances from Picton and Blenheim ferried six patients to hospital, all from the trailer sailer and all believed to have come from Christchurch.

Four had minor injuries and two had injuries described as moderate.

All six were still in Wairau Hospital at 4pm.

None of the occupants of the power boat was injured.

The six people were picked up at the jetty at Waikawa, having been taken there by a private launch.

One of the injured had been thrown into the water, and the other five were picked up from the water after the trailer sailer sunk.

Picton Harbourmaster Alex van Wijngaarden said it would be some time before a clear picture emerged of what had happened.

"We're still looking," he said.