In the 1870 Jules Verne classic "20,000 Leagues Under the Sea," underwater explorer Captain Nemo predicted the mining of the ocean floor's mineral bounty: zinc, iron, silver and gold.
India is catching up with that as it prepares to unearth treasures down below.
The floor of the world's seas is scattered with vast beds of black potato-shaped polymetallic nodules containing copper, nickel, cobalt, manganese, iron and rare earth elements.