Cops have released a set of self-driving boats into Tian'e Lake in Hefei, eastern China, to improve safety after 15 people drowned there in 2016.
Wang Xu, a branch director of Hefei police, said: "If someone struggles in the lake, the patrol boat can use sonar and other underwater detectors to track the location of the swimmer and call for help."
The boats have GPS, cameras and a series of sensors - both infrared and acoustic - so they can track down someone who might have otherwise become stranded. The lake has also been fitted with a number of sensors, 20 in total. These optical and infrared sensors help to "divide" the lake.
Zhang Bao, deputy general manager of Anhui CAS-Huacheng Intelligent Technology, who created the boats, said: "A radio transmitter built on an island in the lake helps the boat divide the water into different sectors."
The three-metre-long boats will be supported on the waters by three drones, which are able to deliver safety equipment such as rubber rings or medical equipment or food to those who need it.
And Wang Xu believe robots will replace lifeguards in the future.
He added: "In the future, most of the lifeguards will be replaced by the robot. The boat, powered by a battery, can be used to patrol rivers, reservoirs, lakes and seas - not only for security purposes but also for environmental surveillance and data collection."