There are many sea-borne creatures that are notoriously difficult to film and photograph. To solve this problem, researchers at MIT have developed SoFi, a rubber-encased robotic fish. Mimicking the movement and look of a real fish, SoFi can swim without disturbing the water as much as other methods which can scare away fish and other creatures. To control the robot, the researchers have encased a Raspberry Pi and a Nintendo games controller in an oil-filled rigid outer shell (pictured below) which protects the innards from water pressure. The controller triggers ultrasonic sounds that are amplified by the Pi and are then picked up by SoFi to change direction. You can read more over at Wired.