Outspoken Virgin Atlantic boss Richard Branson has unveiled a new toy: an underwater "plane" for a voyage to the bottom of the sea. The Virgin Atlantic boss hopes the submarine with fighter jet technology will explore unchartered depths at 35,000 feet.

The $660,000 carbon-fiber prototype "Necker Nymph" will swoop 130 feet under the surface but Sir Richard, 59, is building a stronger version to go deeper than any sub has ever been.

Sir Richard said: "It is very similar to an airplane flying in the sea. You can literally do loop-the-loops." It could eventually reach the Mariana Trench, believed to be the world's lowest spot in the Pacific Ocean.

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US company Hawkes Ocean Technology built the 15-foot winged sub, which has three 360-degree view cockpits and is steered like a plane with a joystick. Film director James Cameron used one of the company's subs to look for underwater inspiration for his 3D blockbuster Avatar.

Sir Richard -- who last month unveiled the world's first commercial spaceship -- told The Sun the sub will be based at his private Necker Island. He plans to use it to take holidaymakers on underwater trips.

He said: "We hope to have submarines dotted throughout the world. A pressurized submarine is nearly completed. But the real challenge is to explore what's going on at the bottom of the oceans."

The ship will live under the umbrella of Branson's Virgin Limited Edition brand, a collection of luxury retreats for the very wealthy. The group includes Necker Island in the British Virgin Islands. Necker Belle will be available at a weekly rate of $25,000, according to Hawkes' Web site.

Read more about Branson's new venture at The Sun.