Green Lakes, near Syracuse, NY

The ponds at Green Lakes State Park are curiously green. Wikipedia tells me that they are interesting for being "meromictic," meaning that different layers of water in the lake never mix. The ponds are pretty super deep, nearly 200 feet, or again so says Wikipedia. The most spectacular thing, though, is these freshwater reefs. Pictured here is "Deadman's Point," so named, I'm told, because somebody drowned when they swam under and got stuck under the reef. Now they're pretty serious about you not swimming there—signs threaten two weeks in jail. As if in compensation, topless bathing is permitted at the nearby beach.