British tycoon Richard Branson may have lost his race to the bottom of the ocean, but not his sense of humor, declaring Friday a faux plan to top his rivals by voyaging to the center of the Earth.

The impossible adventure was announced, tongue jammed in cheek, with the seriousness of a real campaign.

"Sir Richard Branson to launch journeys to the center of the Earth through Virgin Volcanic" the website virginvolcanic.com claims, in one of two teasingly-timed announcements ahead of this weekend.

An early clue that this was a joke was that a press release from Branson's PR people cannot be published until April 1.

The announcement came days after Hollywood director James Cameron grabbed headlines by making history's first solo -- and real -- trip by submarine to the deepest point of the world's oceans: the Mariana Trench in the Pacific.

It was an exploit that Branson, known for his pursuit of ballooning and sailing records, had had his eye on too.

Never mind: Cameron will eat his heart out hearing that Branson says he'll take trendy singer will.i.am of the Black Eyed Peas in a special capsule down into a volcano and from there to the molten center of the planet.

"I have long held a fascination with volcanoes having read Jules Verne's 'Journey to the Centre of the Earth' as a young boy," Branson said on the website.

"Volcanoes are the next great unexplored terrain. What can I say, I lava challenge!"

At the same time as the relatively subtle volcanic spoof announcement, Branson also unveiled a more straightforwardly crackpot plan on his blog -- for a Virgin-branded time machine.

"We've had a slightly frightening breakthrough with a time machine. I've found that we can now go backwards in time but not forwards. Fortunately we can get back to the present," he wrote.

Underneath a picture of him dressed in a white coat inside a cubicle-style machine labeled "Virgin Time Travel," he added: "This could be one of the greatest breakthroughs Virgin have ever worked on.

"Even more exciting than Virgin Galactic or Virgin Oceanic."

Below that was a photo of him emerging from the machine four decades ago, in full 1970s flares and roll-top sweater with a copy of "Tubular Bells" -- the debut hit record of Branson's career-starting Virgin Records -- under his arm.

"As you can see from the photos, I went back to 1972. How far backwards would you like to time travel? Where would you like to go?"