The treaty, whose text was finalized Saturday night by diplomats at the U.N. headquarters after years of stalled talks, will help safeguard the high seas, which lie beyond national boundaries and make up two-thirds of Earth's ocean surface. Member states have been trying to agree on the long-awaited treaty for almost 20 years.

Environmental advocacy groups heralded the finalized text — which still needs to be ratified by the United Nations — as a new chapter for Earth's high seas. Just 1.2 percent of them are currently environmentally protected, exposing the vast array of marine species that teem beneath the surface — from tiny plankton to giant whales — to threats such as pollution, overfishing, shipping and deep-sea mining.

"Two-thirds of the ocean has just been exposed to the will and want of all," said Rebecca Hubbard, the director of the High Seas Alliance consortium of nongovernmental organizations that participated in the negotiations, in a telephone interview Sunday. "We have never been able to protect and manage marine life in the ocean beyond countries' jurisdictions," she said. "This is absolutely world-changing."

Despite U.N. members agreeing to a final version of the text, it is expected to take years for the treaty to be formally adopted by member states and come into force. The United States, in particular, is often slow to ratify environmental treaties — and often will decline to approve them at all.

Once the treaty takes legal effect, nations can begin proposing the establishment of new marine protection areas. Even then, enforcement will remain a challenge. International waters today are a Wild West of sorts, with little to no policing. Illegal fishing runs rampant and some seafood vessels even use slave labor.