At the edge of a vast indoor tank, a team of university students watches intensely as a robotic vehicle attempts to negotiate an underwater obstacle course.
The box-shaped robot, held in place within an outer frame, has been designed by a team from Heriot Watt University in Scotland.
It is designed to complete a series of challenging tasks: passing through a gate without touching any part of the structure, following a moving target, hovering over a stationary target and "parking" in a box.
But there is not a joystick in sight - this robot is designed to navigate the course independently of a human operator.
The sub built at Heriot Watt is one of eight autonomous underwater vehicles (AUVs) vying for top place in a competition called SAUC-E (Student Autonomous Underwater Challenge Europe).
The venue for this contest is the Ocean Basin in Gosport. This is Europe's largest freshwater tank, measuring 120m long, 60m wide and 5.5m deep.
Run by defence research firm Qinetiq, it is mostly used to test models and prototypes of military ships and submarines.
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