Warning – there is a vaguely spidery feel to its motion, so the first video should be treated with care by arachnophobes, particularly just before bedtime.
Besides the intense pressure at depths of more than a few tens of metres, strong tidal currents make it difficult to explore many important underwater locations. The Crabster's role will be to tackle places where the rough conditions don't suit propeller-driven craft. Unsurprisingly, shipwrecks are particularly common where the waters are rough and shallow, so the Crabster will have plenty of targets.
Another advantage to this mode of transport is that it will shake up less material from the ocean floor, assisting visibility. Power comes from an external source, allowing the Crabster to stay underwater almost indefinitely. Four people are required to operate the vehicle; a pilot, co-pilot in charge of lights and the gripping front legs, a navigator and someone to monitor and operate the sensing equipment. This all occurs from a remote station operating out of a shipping container near where the Crabster is deployed, using a 500m tether.
Images produced by the Crabster on its test run in shallow waters can be seen here, along with footage of it being moved in and out of the water