The United States Navy has been using trained dolphins for several years to find mines underwater. The Navy has around 24 trained dolphins that can find mines and the Navy has around 80 dolphins total in the Marine mammal program.
The Navy will started replacing the dolphins with unmanned underwater vehicles starting in 2017. Dolphins are able to use their echolocation capabilities to find underwater mines and warn personnel so that the mines can be avoided and removed.
The unmanned underwater vehicles will use a broadband sonar system to conduct the same task. They will also use low-frequency broadband-sonar to perform a task at a greater distance and longer duration. The unmanned vehicles can also operate without the need for manned support boats or surface-based assistance that the dolphins need.
The Navy compares the dolphin mine hunting program to programs that use dogs to detect bombs and drugs in airports. The dolphins in the Navy program will be used for other tasks.