A floating light installation in the East River tells you when it’s safe to swim there

If you’ve been around NYC for, say, the last 10 years or so, you may have heard of +POOL, a swimming pool in the shape of a plus sign. Besides its appearance, it’s distinguished from other NYC pools by the fact that it’s designed to bob along the surface of the East River, filtering out nasty bacteria and contaminants from the estuary’s brackish H20 to produce 600,000 gallons of good, clean, swimmable fun.

Always on the verge of opening, though never quite doing so, +POOL has been floating around (heh) since 2011, when it began as a Kickstarter campaign. The folks behind the project insist that it’s still happening, but in the meantime, they’re offering something of a placeholder: A water-borne light installation in the shape of +POOL.

Photograph: Iwan Baan

Anchored off Pier 17 at the South Street Seaport, +POOL Light, as it’s appropriately dubbed, measures 50 by 50 feet and is constructed out of LEDs that change color according to the condition of the water—which, according to the +POOL Light website means “indicating when it’s great, or not so great for swimming!” (Question: When is it ever “great” to dive half-naked into the East River?) The website also mentions that scientists at Columbia University’s Lamont Doherty Earth Observatory developed an algorithm that uses environmental data (temperature, turbidity and salinity) collected by sensors at the pier to program the installation (you can also receive the info via an online dashboard app). +POOL Light is on view until January 4, so if you go, bring your trunks, because, hey, you never know when it might be time for a dip.