The SHOAL robotic fish that can detect waterborne pollution in real time is undergoing trials in the port of Gijon in northern Spain. The 1.5m long fish and driven by a dual-hinged tail that enables it to move like a real fish. The fish can either work alone or in a group. It can map which pollutants in the water, and in what concentrations, sending the information to a base station using wifi.

http://www.roboshoal.com/home/robotics