President Danny Faure's call for action on ocean protection, the first-ever live political speech from an underwater submersible, comes from one of the many island nations threatened by global warming.

The president is speaking during a visit to an ambitious British-led science expedition exploring the Indian Ocean depths. Oceans cover over two-thirds of the world's surface but remain, for the most part, uncharted.

We have better maps of Mars than we do of the ocean floor, Faure said.

"This issue is bigger than all of us, and we cannot wait for the next generation to solve it. We are running out of excuses to not take action, and running out of time," the president said from a manned submersible 121 metres below the waves, on the seabed off the outer islands of the African nation.

The president told The Associated Press after his speech that the experience made him more determined than ever to speak out for marine protection.

The oceans' role in regulating climate and the threats they face are underestimated by many, even though as Faure pointed out they generate "half of the oxygen we breathe."

Small island nations are among the most vulnerable to sea level rise caused by climate change. Land erosion, dying coral reefs and the increased frequency of extreme weather events threaten their existence.

During the expedition, marine scientists from the University of Oxford have surveyed underwater life, mapped large areas of the sea floor and gone deep with manned submersibles and underwater drones.

The data will be used to help the Seychelles expand its policy of protecting almost a third of its national waters by 2020. The initiative is important for the country's "blue economy," an attempt to balance development needs with those of the environment.

"From this depth, I can see the incredible wildlife that needs our protection, and the consequences of damaging this huge ecosystem that has existed for millennia," Faure said in his speech.

"Over the years, we have created these problems. We can solve them."

Currently, only about 5 per cent of the world's oceans are protected. Countries have agreed to increase the area to 10 per cent by 2020.

But experts and environmental campaigners say between 30 per cent and 50 per cent of the oceans outside nations' territorial waters should get protected status to ensure marine biodiversity.

Researchers hope their findings also will inform ongoing United Nations talks aimed at forging the first high seas conservation treaty, scheduled to conclude this year.

Australian Associated Press