The Florida Keys: America's Coral Cay Chain and the 3rd Largest Barrier Reef

The Florida Keys are a ~1,700-island archipelago (Monroe County) arcing 180 miles southwest from Miami to Key West. They are the exposed spine of an ancient coral reef tract.

Geography

• Key Largo — Northernmost major island (MM 100).
• Key West — Southernmost city in contiguous US (MM 0).
• ~40 inhabited; rest mangrove islets.
• Overseas Highway (US-1) — 42 bridges, 7-mile bridge (longest).

The Reef: Florida Reef Tract

• 3rd largest barrier reef globally (after Great Barrier Reef, Mesoamerican Reef).
• Living coral area: >58 mi² (150 km²).
• Location: 7 mi (11 km) offshore, parallel to Keys.
• Structure: Bank reef (outer), patch reefs (inner), hardbottom.
• Key species: Elkhorn, staghorn, brain, star corals; gorgonians; 500+ fish species.

Threats

• Bleaching (2014–17, 2023 — record heat).
• Stony Coral Tissue Loss Disease (SCTLD) — 2014+, 90%+ mortality on susceptibles.
• Nutrient pollution (septic, runoff), overfishing, anchor damage, hurricanes.

Protection

• Florida Keys National Marine Sanctuary (1990) — 3,800 sq mi.
• No-take zones (SPAs), mooring buoys, water quality program.
• Restoration: Coral Restoration Foundation, Mote Marine, NOAA Mission: Iconic Reefs.

The Keys are the reef — and the reef is the Keys. Losing one means losing both.