Canadian Coast Guard and Armed Forces personnel are staging a training exercise using Cormorant helicopters in low-level manoeuvers over Sydney harbour.
Police and local fire department dive teams and water rescue units are also participating in the training session.
Cormorants will hover over boats from the Canadian Coast Guard College to lower search and rescue technicians on board during the exercise which began yesterday and continues today.
Coast guard spokesman Pat Donovan said the goal of the exercise is to put personnel on smaller boats to airlift casualties in the event of a real emergency.
The exercise is expected to involve 40 coast guard and 20 Air Force personnel with about 20 from police and fire departments from the surrounding area.