Branson's latest stunt? To plunge new depths...

His past endeavours include space tourism and attempts to circumnavigate the world in a hot air balloon.

Sir Richard Branson, the colourful head of the Virgin Group, is to plunder new depths in his latest venture: exploring the ocean floor in a jet-like submarine. The Virgin Oceanic will see Sir Richard descend to crushing depths of more than 36,000ft.

The craft is no industrial submarine either – it will measure just 18ft long, the entrepreneur said at a news conference in Newport Beach, California.

Sir Richard will go on five dives in two years. The first is set for later this year, when the team plans to explore Mariana Trench in the Pacific Ocean. The Virgin Oceanic will cost less than $10m (£6m) and Sir Richard is hoping that the vessel can eventually take passengers on deep-sea dives.