Meet the Aquabotix SwarmDiver: a tiny underwater/surface vehicle that can be controlled as a single coordinated swap by a human operator. These micro unmanned surface/underwater vehicles weigh 1.7kg, measuring 75cm long. They have vertical dive capability.
These machines can dive to a depth of 50 meters. They have accurate temperature and pressure sensors. They can be deployed in groups to capture data. SwarmDivers are great for oceanography and other areas of research.