The world's largest marine reserve will be created in the ocean next to Antarctica, the countries that decide the fate of the frozen continent have decided.
The historic agreement comes after years of diplomatic wrangling and high-level talks between the US and Russia, which has rejected the idea in the past.
Supporters of the reserve say it sets a precedent for numerous countries working together to protect a large swath of ocean, which falls outside any single nation's jurisdiction.
The agreement covers an area about twice the size of Texas in the Ross Sea.
The deal was clinched after 24 countries and the European Union met in Hobart, Australia, this week. Decisions on Antarctica require a consensus among the 25 members, a hurdle which has confounded past efforts.
The US and New Zealand have been pushing for a marine reserve for years. They first submitted a joint proposal in 2012, but it was rejected five times before Friday's agreement.
Ukraine, China and Russia had expressed concerns in the past, with Russia becoming the final hold-out before the deal was made.
The marine protected area covers 617,000 square miles. There will be a blanket ban on commercial fishing across about three-quarters of that area. In the remaining ocean zones, some commercial fishing will be allowed.
A small amount of fishing for research purposes will be allowed throughout the protected area.
Several countries fish in the waters surrounding Antarctica for lucrative toothfish, which are often marketed in North America as Chilean sea bass.