As someone else pointed out, Jazz has removed all life jackets from their planes. They do stay close to shore.

Also, I just want to point out that on the YVR-YYJ route (along with the other YVR-island flights), it's not just land, but the airports that are close by. If a YVR-YYJ flight had a mechanical problem, it's really within 5-ish minutes of either airport, at the furthest.