RCAF Cormorant helicopter lands near Wood Islands during training exercises with the coast guard. (Brian Higgins/CBC)

A large simulated rescue operation is being held in the waters of the Northumberland Strait Wednesday between Nova Scotia and P.E.I.

Six aircraft, 18 boats, and more than 50 simulated casualties are involved. The coast guard exercise will take place over 65 kilometres of the strait from Charlottetown Harbour east to Wood Islands, P.E.I. and Pictou, N.S.

"It's going to begin with a broken mayday message from a tour boat," said John Drake, a search and rescue preparedness officer with the coast guard.

"As the exercise unfolds and more information comes to light, they're actually going to find out that the tour boat has gone down and again we're talking approximately 50 people on board at the time."

The exercise started at 9 a.m.

A second component will be held Wednesday night, involving search and rescue technicians being dropped by helicopter into the waters near Wood Islands.