Saint Martin and Sint Maarten

The Nature Foundation reports Dutch dive sites spanning shallow reefs to wrecks beyond ordinary Open Water range. Stay within certification and conditions, do not assume wreck penetration, and use a local professional familiar with moorings. Never enter the water from an unauthorized mooring or anchor near reefs. For breath-hold diving use direct rescue supervision and one-up/one-down protocols. For suspected decompression illness, activate local emergency services, give emergency oxygen if available and trained, and contact a dive physician/DAN; do not fly an injured diver without medical direction. DAN suggests at least 12 hours after one no-decompression dive and at least 18 hours after repetitive/multiday no-decompression diving before flying; longer may be prudent, particularly after decompression dives.

The Dutch side has St. Maarten Medical Center/St. Maarten General Hospital in Cay Hill; the French side has Louis Constant Fleming Hospital in Concordia. The Dutch Nature Foundation identifies the nearest decompression chamber as Saba, not as on-island. This does not confirm operational chamber capacity, suitable transfer by air/sea or dispatch availability at the time of an accident. Confirm emergency action plans and coverage for evacuation, repatriation and recompression before departure; local EMS should direct actual emergency transport. Dial the jurisdiction-specific service number first, then DAN.

French reserve: use designated moorings, do not anchor on seagrass/coral, land on protected rocks or take marine material. Commercial companies need specific French-reserve authorization. Dutch Man of War Shoal: comply with separate dive tags, boat registration, one vessel per authorized mooring and no wildlife touching, feeding, fishing or collecting. Its dive moorings cannot be used by snorkelers; the freediving exception is for authorized freedivers. Turtle nests should be left unlit and undisturbed, especially in the March-December broad island activity span. Cul-de-Sac's September 2026 designated sargassum barriers also create explicit no-swim/no-dive zones. Check French reserve guidance, Dutch regulations and port notices before going.