The company, which has been focusing on the Clarion-Clipperton Zone (CCZ) in the Pacific Ocean with a plan to extract cobalt and other battery metals, has added 74,713km2 to its holdings.
The inferred resource of the area under the new licence, its third, is 756 million wet tonnes of polymetallic nodules.
"DeepGreen's expanded polymetallic nodule exploration portfolio in the Clarion Clipperton Zone contains enough nickel, copper, cobalt and manganese to potentially build over 250 million electric vehicle batteries," it said in its confirmation of the takeover.
The deal also expands its data library, giving it 10,450 preserved biological samples, 3,153 line-km of seabed images and 115,591km2 of high-resolution bathymetric data.
TOML's contract had been granted by the International Seabed Authority (ISA) and sponsored by the Kingdom of Tonga. DeepGreen acquired TOML from Deep Sea Mining Finance.
DeepGreen said there are three Pacific Island nations — the Republic of Nauru, the Republic of Kiribati and the Kingdom of Tonga — partnering with it to help with capacity building, employment opportunities and future production royalties.
"We believe now more than ever that the world needs to work together to find solutions to address climate change," said Gerard Barron, CEO and chairman of DeepGreen Metals.