“In the depths of the ocean, there are mines of zinc, iron, silver and gold that would be quite easy to exploit,” said Captain Nemo, hero of Jules Verne’s Twenty Thousand Leagues Under the Sea, in 1870. Now 21st-century technology is confirming his statement, as mining companies, spurred by high commodity prices, prepare to extract metal ore from rich deposits more than a kilometre under water.

The Euroscience conference in Munich heard on Tuesday that marine science and mining technology had combined to make it realistic for the first time to exploit minerals deposited on the seabed in volcanic areas known as ocean ridges, which typically lie 1km-2km below the surface. They are rich in zinc, iron, silver and gold, as well as copper and lead.