At first, I think it’s my imagination—after all, how can the water just glow like that? Sitting on a pirate ship under an almost-full moon, the Aegean below the starboard side seems to sparkle, each ripple producing a new, tiny burst of blue-green wonder. There’s a scientific explanation, I realize, a phenomenon they call, somewhat clinically, and a little poetically, bioluminescence. But for the moment, it’s just magic. A few of my shipmates let the moment take them all the way down to the water, each stroke of their impromptu swim traced with more of that lovely light.    Ancient and alluring, the 5,000-mile Turkish coastline has been drawing adventurers and explorers since (almost) the beginning of time. Known now as the Turkish Riviera, this string of historic towns and hidden beaches lines the Aegean, and the Mediterranean, along the western and southern shores of the country. Sometimes overshadowed by neighboring …