CÔTES DES ARCADINS, Haiti — It was an immaculately clear midsummer morning, a perfect day for diving. No trash had yet washed up on the beach. A dozen volunteers, all excited, some a bit apprehensive, donned flippers and masks and shimmied into the bathtub-warm sea, eager to join a team of eco-divers responsible for surveying, and perhaps one day helping save, Haiti’s endangered coral reefs.

Only one thing stood in their way: For most of them — like Jessika Laloi, 21 — this was their first time swimming in the ocean. Until a few months ago, Ms. Laloi had not even known how to dog paddle.

Now she was wading into the ocean in shorts and a tank top, with a life preserver strapped to her torso, a welcome distraction from the tumult of life since her home collapsed in the earthquake a year and a half ago.

“Diving and swimming is a way of showing you that you are in the environment,” Ms. Laloi said. “You are part of it. You don’t have to destroy it.”