Maritime New Zealand and Police have begun separate investigations, into a fatal boat collision in the Marlborough Sounds

Two boats collided in the mooring area of Okiwi Bay about 7.30 last night.

One person died on the way to hospital, another's in hospital in a moderate condition -- and another person was also injured.

Maritime New Zealand says it's carrying out interviews, scene inspections and examining documents before deciding on further action.

Police say they're also investigating the tragedy.