Does the vengeful spirit of a dead girl lurk in the depths of Egypt’s Blue Hole? Superstitious locals say she’s to blame for the Red Sea beauty spot’s reputation as `the most dangerous dive site on earth’.

Monty Halls braves the rip currents off a remote Japanese island to investigate claims of a lost civilisation sunk beneath the waves. Are the underwater terraces, archways and giant head evidence of a Japanese Atlantis or just an extraordinary natural rock formation?

It’s an underwater mystery to rank with the Marie Celeste – an 1870s grain schooner, apparently undamaged, lying in 200 feet of water, and abandoned by her crew, who all disappeared without trace.

Monty Halls and his team are off on a boys own adventure looking for treasure in Namibia, one of the last places that you would imagine for a diving trip. They are heading to Lake Otjikoto, in the north of the country, where they hope to find a safe full of German gold coins, rumoured to have been thrown into the lake in 1915.