The economics of mining has changed, though. Industrial commodity prices, despite recent falls, are much higher than in the 1970s, and technology has advanced. That means it may now become profitable to exploit the manganese crusts and other minerals recently discovered. Several countries certainly hope so. In the past five years China, France, Germany, India, Japan, Russia, South Korea and a consortium of east European countries have all been awarded licences by the International Seabed Authority to explore mining possibilities on the deep-ocean seabed, and a Canadian company, Nautilus Minerals, hopes next year to be the first deep-water mining company to start production. Its plan is to bring up ore containing copper and gold from the bottom of the Bismarck Sea north of Papua New Guinea, using technology developed by the offshore-oil industry.

That industry, with its own purposes in mind, is also keening to move into deeper waters, especially in the Arctic. Rising temperatures and melting ice make Arctic extraction easier, and American government scientists now believe that 90 billion barrels of oil and vast amounts of natural gas still lie beneath the Arctic. Nearly 85% of these deposits, they think, are offshore.

The thought of Arctic oil has quickened more than pulses. Canada is establishing a year-round Arctic presence on land and sea as well as in the air. Denmark is trying to prove that a detached part of the underwater Lomonosov ridge is an extension of Greenland, which is Danish territory. And Russia has staked a claim by sending a submersible to plant a corrosion-resistant titanium flag some 4km below the North Pole.

... contd.