But that will soon change. In April, the Navy unveiled its plans for Knifefish, a torpedo-shaped, underwater robot that would roam the seas for up to 16 hours, looking for mines. The 7m- (20ft-) long unmanned underwater vehicle (UUV) is still in development, but should be ready by 2017, and will use sonar to hunt mines. “The Knifefish UUV is ultimately intended to be the replacement for the marine mammals,” Linkous says.