After years of conservationists pushing for better protection of the pristine Antarctic waters from exploitation, a "momentous" agreement was finally reached yesterdaywith Russia dropping its long-held opposition to the plan.
Proposals to create two massive marine sanctuaries in the Ross Sea and East Antarctica were tabled in 2012, jointly accounting for more than 2.5 million sq km.
The Antarctic is one of the world's last wild frontiers, and it has some of the most pristine marine ecosystems left on earth, with many habitats yet to be studied.
The Southern Ocean, which is mainly untouched, is seen as a critical laboratory for scientists monitoring climate change effects .
The area is also home to over 10,000 unique polar species, such as most of the world's penguins, whales and seabirds, as well as commercially targeted krill.