I was just on Air Canada's Website. If you scroll down you will see a post on the right hand side saying "Suspension of flights to St. Maarten. Click on it and it says the following:

October 27, 2017

Due to the impact of Hurricane Maria on the island, Air Canada has suspended all flights to St. Maarten for the 2017-18 winter season.

A goodwill policy is in place so affected customers can obtain a refund.

If your travel is affected, contact Air Canada Reservations (1-888-247-2262). If you purchased your ticket with AeroplanExternal site which may not meet accessibility guidelines. or Air Canada Vacations,please contact them directly.