University of Wisconsin Madison College of Engineering
An inflatable ring about 50 feet in diameter on the lake surface to test of water-mixing equipment.  The inflated device brings water from the lake bottom to the surface.

A device that resembles a parachute with an inflatable ring floats to the lake surface while being utilized in a test of water-mixing equipment near the Limnology pier on Lake Mendota. The experiment brings water from the bottom of a lake to the surface and raises the temperature of the water. Photo: Bryce Richter.