A high-tech mission to uncover the secrets of our seas has revealed a ‘hotspot’ for marine wildlife off the southern coast of Wales.   The mission saw an unmanned underwater ‘glider’ travel to an area around 50 miles to the south west of Wales called the Celtic Deep, which is a haven for wildlife but also an extremely busy shipping route and fishing ground. The glider travelled 600km in 30 days, undertaking nearly 3000 dives from the sea…