Somewhere between Florida, Bermuda and Puerto Rico there is a stretch of warm Atlantic water that people have been telling stories about for sixty years. Tonight we go out there slowly, and we take our time. The Gulf Stream running north like a river inside the ocean. The Sargasso Sea, the only sea on earth with no shores, held in place by four currents turning in a great slow ring, with a floating golden forest drifting on top of it and small creatures living in that weed who will never in their lives encounter a beach. And five miles down, at the southeastern corner, the deepest water in the whole Atlantic.

We spend time with the real losses, because they were real and the people in them deserve better than being footnotes. A collier called the Cyclops with three hundred and six men aboard. A five-masted schooner found aground at Diamond Shoals with a meal half prepared in the galley. A training flight out of Fort Lauderdale on a December afternoon in 1945, and the aircraft sent to look for it. Then we look, gently, at where the mystery itself actually came from — a wire story in 1950, a magazine article in 1964 that drew three lines on a map and gave the enclosed water a name, and a librarian who went back to the original records and found something quieter than anyone expected.

Nothing here is frightening and nothing is sensational. The theories are held lightly and set down again — the moving agonic line, methane trapped in ice on the continental slope, rogue waves confirmed by satellite. Everything uncertain is flagged as uncertain. The episode ends where it always does: a long, layered wind-down over warm water and slow stars, with no need to keep following, and full permission to stop listening and sleep. Narration only, no music, no sudden sounds, nothing that will wake you.