A 1,000-tonne ship is exploring the far-flung South Pacific for riches buried beneath the waves, spearheading efforts to dredge the tropical waters for industrial deep-sea mining.

Fringed by sparkling lagoons and palm-shaded beaches, Pacific nation the Cook Islands has opened its vast ocean territory for mining exploration.

Research vessels roam the seas searching for deposits of battery metals, rare earths and critical minerals that litter the deep ocean's abyssal plains.

The frontier industry is likened by some to a modern-day gold rush, and decried by others as environmental "madness".

AFP visited the sunburst-orange MV Anuanua Moana at the Cook Islands' sleepy port of Avatiu, where it loaded supplies before setting sail for the archipelago's outer reaches.

"The resource in our field is probably in the order of about US$4 billion in potential value," said chief executive Hans Smit from Moana Minerals, which converted the former supply ship into a deepwater research vessel.

It is fitted with chemistry labs, sonar arrays and sensors used to probe the seabed for coveted metals.

For two years it has sailed the Cook Islands, halfway between New Zealand and Hawaii, gathering data to convince regulators that deep-sea mining is safe.

While exploration is far advanced, no company has started mining on a commercial scale.

"I want to be mining before 2030," Smit said from the ship's tower, as whirring cranes loaded wooden crates of heavy gear below.

"Absolutely, I think that we can."

Large tracts of seabed around the Cook Islands are carpeted in polymetallic nodules, misshapen black globes encrusted with cobalt, nickel,........

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