Seabed minerals explorations within the EEZ of the Cook Islands were reported to have been first carried out by the US and USSR research vessels in the 1960s. These surveys were later picked up by other companies and consortia in the early 1970s and continued until the late 1980s that resulted in the discovery of significant manganese nodule resources. These early seabed mineral investigations were mainly focused on identifying mineral occurrences and understanding their mode of occurrence and the geological setting in which they occur. Apart from efforts to identify other mineral types such as metalliferous sediments, cobalt-rich crusts, phosphate and precious coral, manganese nodules was the chief target of seabed mineral prospecting in the offshore areas of the Cook Islands.
Early surveys were not carried out in a reasonably detailed and systematic manner hence manganese nodule resources could not be quantified. It was not until the Japan-SOPAC Cooperative Study that commenced in 1985 for twenty-one years that any serious attempt was made to estimate the manganese nodule resources within the Cook Islands’ EEZ. Four exploration cruises (i.e. in 1985, 1986, 1990 and 2000) were carried out in the Cook Islands as part of this programme. The 2000 survey was conducted in the central eastern part of the country’s EEZ.
The East-West Centre undertook a study in 1993 in conjunction with SOPAC and MMAJ based on all available data at the time. They concluded that more exploration is needed to define the resource and determine the most favourable area before a decision could be made to develop the resource. Further they noted that “…nodule mining in the Cook Islands if proven economically feasible is still at a minimum a decade or more in the future”
In a 1995 East-West Center economic feasibility study, 652,000 km2 of the Cook Islands EEZ, where nodule abundances are greater than 5 kg/m2, were estimated to contain 7,474,000,000 tons of nodules. These nodules were estimated to contain 32,541,000 tons of cobalt, 24,422,000 tons of nickel and 14,057,000 tons of copper. In addition, there is the prospect of rare earth minerals being located in the mud on the seabed floor.
A 1996 economic assessment by the Bechtel Corporation of San Francisco concluded that a nodule mining project for cobalt (Co) in the CIEEZ, given a large number of assumptions, would be feasible so long as the price of Co did not drop below US$16.75 per pound in April l996 dollars.
In 1998, an informative report by Stuart Kingan, a scientist resident in the Cook Islands, was prepared for the government, with the hope of attracting foreign investment in DSM exploration and mining. Since then, the progress of the developmental process in DSM in the Cook Islands has continued, but with varying degrees of activity.
In 2000, a Norwegian study building on the Bechtel study determined that the cobalt price then at $US15 per pound made investment in any DSM venture uneconomic.
Despite that setback, successive Cook Islands governments have been proactive, with the assistance of international partners, in taking the necessary steps to develop a national framework for the regulation of its nation’s future in deep sea mining within its EEZ.
Below are expeditions that have been carried out in Cook Island waters (EEZ) since the late 1970s:
research vessel & year of survey
RV Tangaroa (1974)
Rarotonga, Cook Islands
MV Ravakai (1976)
Area between Rarotonga and Penrhyn
Manganese nodules, Metalliferous sediment and Phosphate
RV Acheron (1977)
Southern Group, Cook Islands
Precious coral, Manganese nodules
RV Machias (1978)
Penrhyn and Samoa Basins, Nearshore waters of the Cook Islands
Manganese nodules and Precious Coral
RV Machias (1980)
Northern Cook Islands
Manganese nodules and Precious coral
RV Machias (1980)
East of Penrhyn Island, Penrhyn Basin, Penrhyn, Manihiki, Nassau Islands
Manganese Nodules, Precious coral and Phosphate
RV Sonne (1980)
RV Hakurei Maru (1980)
South Penrhyn Basin
MV Ravakai (1983)
Slopes of Rakahaga and Manihiki Atoll
RV Hakurei Maru (1983)
South Penrhyn Basin
RV Hakurei Maru 2 (1985)
Western Penhryn Basin, eastern margin of the Manihiki plateau and the North of Penrhyn Island.
HMNZS Tui (1986)
Manihiki Plateau and adjacent Southwest sea areas
Cobalt-rich crust, Manganese nodules
RV Hakurei Maru 2 (1986)
Western edge of the southern Penhryn Basin (to the east of the Manihiki plateau)
RV Moana Wave (1987)
Cook Islands: Suwarrow trough, eastern Manihiki Plateau, Rakahaga-Manihiki island area
Cobalt-rich crust and Metalliferous sediments
RV Thomas Washington (1987)
Northern Cook Islands and adjacent High Seas
Manganese nodules, Cobalt-rich crust, Deep sea sediment
RV Sonne (1990)
North-east edge of Manihiki Plateau
Complex of Volcanic Cones and mineral resources
RV Hakurei Maru 2 (1990)
Southern Cook Islands
RV Hakurei Maru 2 (2000)
Central Coo Islands (i.e. Southern Penrhyn Basin)
RV Grinna (2019)
Central Cook Islands (CIIC-SR reserve area)