Light Touch

The hybrid remotely operated vehicle (HROV) Nereus normally operates in one of two modes: with a fiberoptic tether that allows technicians to control the vehicle from the surface, or as a tetherless, fully autonomous underwater vehicle. After a recent engineering cruise in Guam, however, it now has a third operating mode that also allows it to be controlled by a pilot and to transmit video and data to the surface, but this time via an optical modem that does not require a physical connection to the vehicle. (Photo by Cliff Pontbriand, Woods Hole Oceanographic Institution)