An expedition to reveal the secrets of a mysterious huge hole at the bottom of the Atlantic Ocean starts today.

In a voyage inspired by the spirit of the writer Jules Verne, a £40 million British research ship will set sail on its maiden voyage to open what scientists are calling “a window into the Earth”.

RRS James Cook will spend six weeks sailing over the Atlantic Ridge taking measurements of the gaping hole on the ocean floor that has baffled experts.

Scientists are trying to find out why hundreds of square miles of the Earth’s crust is missing, giving a rare glimpse of the mantle, the planet’s interior, underneath.

The hole in the crust covers a huge area of a mountain range hidden beneath the waves and has puzzled scientists because it defies conventional tectonic plate theories.

The crust should be about four miles thick but instead there is a layer of the Earth’s mantle at the bottom of the ocean.

The hole would have been expected to become filled with volcanic material as it was formed as the Atlantic tectonic plates pulled apart at a rate of 2cm a year but it is filled instead by the mantle.

Chris MacLeod, of Cardiff University’s School of Earth, Ocean and Planetary Sciences, is one of the leading scientists on the expedition which will take detailed sonar measurements of the ocean bottom.

Researchers, who set sail from Tenerife, will send a robot submarine to the foot of the range 16,400ft beneath the surface to drill for samples of the mantle.

Using the craft’s cameras, the researchers hope to be able to see the hole, which Dr MacLeod described as “a window into the Earth’s interior”.

The mountains rise 13,000ft from the sea floor, 3,400ft below the waves, and core samples will be taken at a range of depths. Dr MacLeod believes that the expedition will reveal how far the hole in the crust extends along the ocean floor and how it was formed.

Dr MacLeod said: “It doesn’t quite fit the generally accepted model of plate tectonics. We hope to get a direct insight into the processes that go on in the Earth. It’s an essential part of the basic understanding of how the Earth works.”

Crust formation was “a fundamental mechanism of the Earth and affects the ocean chemistry”, he added.

He said that there were two main theories as to why the hole formed and suspected that the answer was likely to be a combination of the two.

In one, a hole formed as the tectonic plates pulled apart but instead of the mantle pushing up in melted form, or magma, it was lifted in a solid chunk. The second theory is that the crust was somehow ripped sideways, leaving a gaping hole over the mantle. The ship that will be home to the team of nine male and three female researchers, was built to replace the aging RRS Darwin. It was funded by the Natural Environment Research Council and the Department of Trade and Industry’s Large Scientific Facilities Fund.

It has been crammed with multidisciplinary equipment and facilities that will allow researchers to work anywhere on the world’s oceans.

For Dr MacLeod the use of the ship is an unrivalled opportunity to answer some of the world’s mysteries and is confident the vessel will be invaluable: “It’s on its maiden scientific voyage and it’s probably the most advanced research ship in the world,” he said.

The RSS Cook’s crew will hope to avoid the dangers encountered by Captain Nemo and his acolytes in Verne’s 19th-century classic Twenty Thousand Leagues Under the Sea. Nemo’s hubristic thirst for scientific knowledge sends his crew into a fatal encounter with a group of giant squid in the Atlantic.

In Journey to the Centre of the Earth, Verne’s explorers are attacked by dinosaurs after attempting to reach the planet’s crust through a dangerous volcano.

Monitor the expedition and live link to ship: www.noc.soton.ac.uk/gg/classroom@sea/JC007/

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