"Looks like an opening at 3 degrees to port. Keep it going dead ahead."

Captain Paul Rudzycki radios down from the crow's nest high above the ship.

Around us, a jigsaw of fractured sea ice stretches as far as the eye can see. The occasional iceberg looms, intense blue below the surface in the morning sun.

The captain guides our way through leads in the ice, the bow pushing forwards towards open water. Here and there a couple of penguins potter about, leopard seals just lying there, raising a head as we pass.

We're a little way east of the Antarctic Peninsula, hoping to reach the 64th parallel, the beginning of what could be the largest protected area on Earth.

Not many ships venture this far and little is known about what lies beneath the surface. The Arctic Sunrise, our Greenpeace host vessel, has already had to turn back once, this Antarctic summer.

But we make steady progress and after 48 hours of nudging, retreating and bypassing, eventually, the ship breaks through to the isolated sanctuary zone.

Nothing has changed in what we see across the enormous icescape but It's an important moment for the Greenpeace campaign team.

"I checked on the satellite and there's one other ship with us here in this entire space across the Weddell Sea," says campaign leader Will McCallum.

'People want this to happen'

We're just on the fringes of the proposed protected zone, which would safeguard a vast 1.8 million square kilometre area, all part of a growing push for large-scale protection of the world's oceans.

Last year a huge area of the Ross Sea on the other side of the continent became a Marine Protected Area.

The Weddell Sea proposal put forward by Germany and backed by the EU, comes up for discussion in October when the governments responsible for the conservation of Antarctic waters (CCAMLR) come together in Hobart.

"It's been acknowledged there's a global imperative to protect at least 30 percent of the world's oceans by 2030," said McCallum. "This is in order to ensure the health of our seas and mitigate the impacts of climate change."

McCallum points to the Greenpeace petition backing the Weddell Sea proposal, it's already collected more than a million signatures. "This campaign seems to have gripped the public imagination," he said. "People have a resonance with Antarctica and its spectacular wildlife, people want this to happen."

'Vested interests'

Of course, there are many with vested interests who would be keen for the sanctuary proposal not to go through, the krill fishing industry for example.

Under the terms of the bid, all fishing would be banned, as would any kind of direct human impact like oil drilling and deep sea mining.

It's hard to imagine any human influence here as the Arctic Sunrise gently pushes through a sea of ice heading back for the Antarctic Peninsula. A lone ship in an unexplored sea. It cannot feel more isolated, remote, and just stunning.

Of course, that's the point of the campaign, to protect the Weddell Sea now, while it's still in good shape, with an incredibly diverse and rich ecosystem.

And as we go, the clouds morph and shape and colour into a fantastic, unworldly painting across the evening sky at the ends of the Earth.