Tasman Bay will be lit by a succession of emergency flares from 7.20pm -8.45pm on Sunday as part of training for the Search & Rescue organisation.
Parachute and hand-held flares will be activated from vessels in two positions on Tasman Bay.
Search & Rescue says the idea is to train rescuers on judging the position of flares so people in distress at sea can be more easily found.
Vessels will be alerted before each flare display, so they are not mistaken for a real emergency.
