The treaty, which took 15 years of tough negotiating to be approved, aims to protect vital marine ecosystems that are threatened by pollution. It requires 60 ratifications before coming into force.

UN members finalized it in March 2023, then formally adopted it. The treaty received 70 signatures in last year's United Nations flagship week -- not ratifications, but indications of willingness to ratify it eventually.

That number has now reached 104.

Five new countries -- East Timor, Singapore, the Maldives, Bangladesh and Barbados -- ratified the treaty during this high-level week of the UN General Assembly, bringing total ratifications to 13.

Campaign groups still hope the treaty will come into force in 2025, but say ratifications are badly lagging.

"Whilst this week's progress is welcome, there is a sense of complacency from some countries, and we would have expected more to have taken the opportunity of ratifying this week," environmental campaigners Greenpeace said.

"It is important that political momentum is kept high and countries finalize their ratification processes as soon as possible."

- 'Incredible week for the ocean' -

"What an incredible week for the ocean," the conservation-minded High Seas Alliance said in a post on X.

But it was "time to step up the pace and sprint to the finish line," Rebecca Hubbard, director of the NGO coalition, said this week.

The high seas begin where the exclusive economic zones of countries end -- at a maximum of 200 nautical miles (370 kilometers) from shore -- and therefore fall under the jurisdiction of no state.

Although the high seas account for almost half the planet's surface area and over 60 percent of its oceans, they have long been ignored by environmental efforts.

The new treaty's flagship tool is the creation of marine protected areas.

Conservation measures currently cover just 1 percent of the high seas.

But in December 2022 in Montreal, at the UN's Conference of the Parties (COP15) on biodiversity, all of the world's nations pledged to protect 30 percent of the planet's landmass and oceans by a summit set for 2030.

Activists say the new treaty will be vital to meeting that goal, adding to the urgency of the quickest possible ratification.

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