His girlfriend might not be so into it, but Elon Musk's self-proclaimed love of digging holes in the ground is fueling the billionaire entrepreneur's latest project – to increase the speed of tunnel boring by up to 1,000%.

Speaking at the first Hyperloop pod competition, set up to find the perfect design for train carriages designed to travel at more than 700mph, Musk said he wants to "get people excited in new forms of transport... do things in a way that is not just a repeat of the past, but to explore the boundaries of physics and see what is really possible."

The Tesla and SpaceX boss went on to say, with a laugh, that he has started digging "a giant hole" at the SpaceX headquarters in California. "I find holes in the ground exciting," Musk said. "I was discussing this with my girlfriend, she doesn't find it exciting, but I thought it was really great."

Musk's digging comes after a series of tweets in December 2016 proposing the idea of creating "The Boring Company" to dig underground tunnels for roads which would help reduce congestion on the surface. In January, and dispelling any belief that he was joking, Musk tweeted again to say he had made "exciting progress on the tunnel front".

Improving tunneling speed while maintaining safety is Musk's ambition with this project. Speaking at the Hyperloop competition, he said: "We're just trying to figure out what it takes to improve tunneling speed. Somewhere between 500 and 1,000% is I think possible. If you apply a limit-of-physics approach we'll see how far we can get."

'We have no idea what we're doing'

But the project is in the very early stages of development. Musk added: "We're just sort of muddling along, we've no idea what we are doing, we want to be clear about that... [but] I'm actually quite optimistic that tunneling can be improved by at least fivefold, maybe tenfold, and that's really key to a lot of technologies: road tunnels, Hyperloop tunnels, train tunnels."

Musk has a habit of proposing revolutionary ideas which at first appear impossible but later become a reality. With Tesla he has made electric cars affordable and with a long enough range to replace internal combustion in many cases. At SpaceX he has successfully created reusable rockets which land themselves, and has plans to colonise Mars, while a new branch of Tesla will create and sell solar roof panels which look like conventional tiles.

Hyperloop, a train levitating on magnets and driven through a tunnel with most of its air removed at over 700mph, was proposed by Musk in a white paper in 2013, and is now being made a reality by several different companies.