Excerpt from
independent.co.uk

It is one of the world’s last frontiers and has seen fewer visitors than the moon. And that – for the being at least – is how it shall stay.

Sir Richard Branson has shelved plans for a submarine to take tourists to the bottom of Pacific’s Mariana Trench, after technical hobbled the grand ambitions of his much-trumpeted Virgin Oceanic project.

The is a second blow to Branson’s adventurer dreams in a matter of months, after a Virgin rocket crashed on a test flight in California’s Mojave Desert, killing a pilot.
Virgin Oceanic’s DeepFlight Challenger was launched in 2011 the entrepreneur’s familiar fanfare. Under the plans, wealthy passengers or “aquanauts” up would pay up to $500,000 (£318,126) for a five-dive package labelled as “the last great challenge for humans”.  

As well as exploring the Mariana Trench – a  36,000ft- abyss is deeper than Mount Everest is tall, with access so risky and complicated that it has had just three human visitors since its formation nine million years ago – the submarine was due to dive the Puerto Rico trench 28,000ft below the surface of  the Atlantic, the Molloy in the Arctic, South Sandwich Trench in the Southern Ocean and Diamantina trench in the Indian Ocean.

But yesterday the Sunday Telegraph reported that Deepflight, the company contracted to the submarine, could not the project because their vehicle could only be safely used for one dive.
The underwater mission to have stalled indefinitely. The Virgin Oceanic website – which had promised “five dives, five oceans, two years, one epic adventure” – no longer exists, reportedly taken down earlier this year.