Guinness-recognised as the brightest bioluminescent bay in the world, up to two million dinoflagellates per gallon. Every…Guinness-recognised as the brightest bioluminescent bay in the world, up to two million dinoflagellates per gallon. Every paddle stroke throws blue-white fire, fish leave glowing trails, and dragging a hand through the water leaves a comet tail. On a truly dark night it is the most extraordinary thing on this entire list. A near-enclosed mangrove bay whose narrow mouth traps the organisms and whose mangroves feed them vitamin B12. Vieques was a US Navy bombing range until protests forced closure in 2003, the restricted access is partly why the bay survived. Swimming and sunscreen were banned after biologists showed both were killing it; the bay mysteriously went dark in 2024 and recovered, a reminder to verify status before promising it. Anchorage: Anchor outside in Bahía Salina del Sur area; motorised entry to the bay is restricted, licensed kayak tours only. Swimming is prohibited. Hazards: Anchor outside in Bahía Salina del Sur area; motorised entry to the bay is restricted, licensed kayak tours only. Swimming is prohibited. Meer