A birdwatching society has spoken of the "tragic loss" of five of its members

Up to 11 bird enthusiasts were on board when their boat capsized off Goose Bay in Kaikoura yesterday - it's believed to have collided with a whale.

Five people died and six others were rescued.

The Nature Photography Society of New Zealand says they're saddened by the loss of its members during a trip yesterday.

They say they're thoughts are with the families who have lost loved ones.

Maritime investigators from across the South Island have been sent to the scene where a vessel flipped.