New Zealand decides this week whether to approve an underwater iron-ore operation that would likely become the world's first commercial metals mine at the bottom of the sea. A green light to allow New Zealand's Trans Tasman Resources Ltd to start iron-ore dredging off the country's west coast will encourage others looking to mine copper, cobalt, manganese and other metals deeper on the ocean floor but worried about regulatory hurdles. Along the Pacific Rim of Fire, as deep as 6,000 metres underwater, volcano crusts, "black smoker" chimneys and vast beds of manganese nodules hold promise for economic powers like China and Japan as well as many poor island states busy pegging stakes on the ocean floor.