Key West

A Key West diving day starts on the island. Finz, Dive Key West and Lost Reef Adventures are on Peninsular Avenue, North Roosevelt Boulevard and Margaret Street by the Bight, and Lost Reef runs two trips a day. The reef line lies about 10 km south and southeast of town, with Eastern Dry Rocks 11 km out and the Vandenberg roughly 10 km offshore. Boats tie into the sanctuary's free mooring buoys, since anchoring on living coral is prohibited, and Sand Key, Rock Key and Eastern Dry Rocks are close enough to dive on one outing. Cannonball Cut has no buoy and is run as a drift. Shore diving barely figures: State Harbor has a shore entry but is an oily harbour basin locals use for lobster.

The Vandenberg is what sets Key West apart from the Upper Keys: a 1943 hull converted in 1964 into a missile-range instrumentation ship, 159 m long, sunk on 27 May 2009 as the world's second-largest artificial reef after the carrier Oriskany. Its stacks, masts and antennas were trimmed to leave 12-14 m of clearance, and the hull runs down to a seabed at nearly 45 m, so gas and no-decompression limits end the dive rather than the wreck. The upper decks sit within recreational range and the hull below is technical territory; Dive Key West asks for Advanced Open Water plus a deep dive within 12 months. The share of Keys dives on artificial reefs rose more than fourfold after the sinking.

The reefs are spur-and-groove coral fingers split by sand and rubble channels, from the surface at Rock Key and Eastern Dry Rocks to 12 m at Western Sambo and 18 m over Cannonball Cut. Rock Key's crevices are unusually deep and hold grouper and morays; Joe's Tug lies over a reef in 18-21 m, and the Cayman Salvager, a 57 m buoy tender sunk in 1985, sits upright in about 29 m with resident goliath grouper. Current is the variable: the moored reef sites are easy, but the outer sites without buoys are drifts and the Vandenberg sits in open water where current has to be planned for. Sourced visibility runs from about 5 m on the Sambo reefs in winter to 18 m on the Vandenberg in a good month.

All of it lies inside the Florida Keys National Marine Sanctuary, whose January 2025 Restoration Blueprint rule redrew the zones. Sand Key and Eastern Dry Rocks remain Sanctuary Preservation Areas, no-take except catch-and-release trolling at Sand Key; Western Sambo's Ecological Reserve is now a Conservation Area extended to the 27 m contour (90 ft); Eastern Sambo stays research-only; the Rock Key preservation area was eliminated, so older guides calling it an SPA are stale. The Haystacks on Western Sambo take snorkellers and all levels, and Marker 32 is an easy first dive. Divers set on the Spiegel Grove or Christ of the Abyss should base in Key Largo; Looe Key is dived from Big Pine Key.