Plus Pool grew out of a 2010 brainstorming session between Mr. Coates and his design partner, Jeff Franklin, and their friends, Dong-Ping Wong and Oana Stanescu, who at the time ran another design firm, Family New York. They lamented that New Yorkers are surrounded by water but live largely cut off from it.

“We suggested Plus Pool as a lark,” Mr. Coates said. “We had no idea about water quality, about how public parks were built, maintained and functioned.” (Perhaps he did not remember the famous scene in “Manhattan” when Woody Allen trails his hand in the water during a romantic boat ride and it comes out filthy.)

While Plus Pool may still be little more than a computer rendering, this week its founders unveiled a sculpture in the East River, titled “Plus Pool Light.” The sculpture, funded by the National Endowment of the Arts, Heineken and the Howard Hughes Corporation, will float for three months off Pier 17 in Manhattan’s Seaport District.

Made of aluminum and PVC and one-fourth the size of Plus Pool, the sculpture will change colors based on water conditions and animate based on other conditions, such as current direction and clarity. Teal means it’s safe to swim, pink means watch out for the sewage. The animating lights use data from sensors at the site and an algorithm developed by scientists at Columbia University’s Lamont-Doherty Earth Observatory and the tech firm Reaktor.