From the ship's deck, there nothing to see but deep blue water, not the remotest sign of a marine paradise that lies just a few meters below the waves.

Volunteers use plastic waste floating in the sea to form a 68-meter-long "sperm whale" in Nantong, East China's Jiangsu Province on Monday. Hundreds of volunteers took part to raise people's awareness to protect the ocean after World Oceans Day, which falls on Saturday. Photo: VCG

Vema, an underwater mountain around 1,000 kilometers off the west coast of South Africa, is a stunning marine haven.

Greenpeace researchers braved choppy seas to explore the site, seeking to monitor the impact of a trawling ban and clues of the planet's climate crisis.

Armed with high-resolution cameras, divers clad in orange-and-black dry suits embarked on what was a daily ritual, disappearing underwater to capture life on the seamount.

They emerged with photographs and video footage of a site flourishing with fish, lobsters and marine plants, thanks to a moratorium on fishing. 

In 2007, the South East Atlantic Fisheries Organization (SEAFO) banned bottom trawling on Vema and other seamounts. 

On Vema, overfishing had brought a local species, the Tristan rock lobster, to the brink of extinction.

Slightly over one percent of ocean areas, those lying outside national jurisdictions benefit from some form of international protection, according to the UN's Ocean Action website.

Activists want more oceans to be protected as nature reserves.

Vema is fortunate to be one of the very few areas of the deep seas that enjoys such a shield.

The biologists said the results proved the positive impact of legal protection.