Billionaires torn between buying a mansion and a superyacht can now have the best of both worlds.

Desginers from Monaco yachts company Wally and the high fashion house Hermès have collaborated on creating plans for a 58m "moving island".

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The WHY 58x38 can comfortably house 16 guests and 24 crew across 3,400m², which includes a 25-metre swimming pool, cinema, music room, dining room and a 30m beach.

The gigayacht boasts a maximum speed of 14 knots and is estimated to cost $160 million when built.

"Everybody's dream is to live on an island, in complete freedom, without constraint, with the independence that only self sufficiency can provide," said Wally's president, Luca Bassani Antivari.

"A piece of land with a beautiful villa partly fulfils this aspiration because it is static. A yacht offers the freedom to move, but does not have the space of a property. WHY has it all."

If you were worrying what it might cost to power this baby, then fear not. The designers have aimed to make it as eco-friendly as possible.

With solar panels generating 500kw a day the designers say you could cross the Atlantic four times without refuelling.

See more pictures in our gigayacht gallery.