From the Greenpeace Climate Rescue Blog Swirling vortices, bright blue rivers, earthquakes, icequakes and 24-hour sunshine. Welcome to the weird world of the Arctic Sunrise, at Petermann Glacier, 81 degrees 11.272 minutes north, 61 degrees 50.892 west. To be exact. For over week now, the Arctic Sunrise has been at Petermann Glacier in northwestern Greenland, where, according to my morning Google Alerts we had a 6.1 earthquake yesterday, at 17:11 local time. No one on board admits to noticing it, despite the epicentre occurring just a few hundred kilometres south of us in Baffin Bay. The three glacier scientists on board are checking their data for the period, to see if the glacier reacted in any way.

Petermann Glacier the largest floating glacier in the northern hemisphere is starting to showing wear and tear, even though we've only been monitoring it for a little while. There's four 'ice islands' that we expect to break off within the next year or so. The most likely, the gargantuan 100 square kilometre piece "A" contains, according to calculations by Jason and myself, around 5 billion tonnes of ice. Since we arrived, some of the cracks between these sections of ice have started to widen.

We don't know when the break will happen, but we're planning on being on location for some weeks.

Time passes strangely here –it's hard to go to bed, when the sun is shining 24 hours a day. That sunshine has been beating down on the ice - we've measured the temperature at the ship at up to six degrees Celcius at times. Up on the glacier, the day progressed, the trickles and torrents of water increased, and at the front, more sea ice and 'bergs have been breaking away. Most people on board have now had a chance to get out and experience the scale and beauty of glacier first hand – and I'm currently trying to persuade, bribe, cajole and perhaps blackmail some of them into blogging their experiences.

Up north of here, where we saw the polar bear last Monday, the Lincoln Sea ice bridge has started to collapse. It's called a bridge, because when looked at via satellite, the sea ice is held back by a frozen barrier that's keyed like a bridge. However, once the bridge breaks goes, the Nares Strait, at the moment practically free of ice willl flood with ice floes drifting south, making life complicated for the Arctic Sunrise. We may have to take evasive action.

But speaking of bears, just after dinner yesterday, Arne shouted down 'two polar bears!' Crew members were out on the bridge wing in seconds, scanning the glacial ice dunes, to spot what turned out to be three bears, a mother and two cubs. They could be seen with binoculars from where the Arctic Sunrise is moored, before ambling off out of sight, presumably on their way to some seal hunting lessons. We're keeping a close eye for reappearances.

Over the last week, the three scientists on board – Jason, Alun and Richard, have been busy deploying all kinds of scientific equipment onto the ice, the cliffs above the glacier, and the ocean in front of it. The time-lapse cameras are clicking away 1,000m above the ice, while Jason has placed another on the glacier itself to show movement between ice and the cliffs. Arrays of GPS units deployed by Alun have record not only the overall travel of the glacier, but changes of position of parts of the glacier, relative to one another as well as giving data on the twisting and turning of the ice flow, in three dimensions.

Richard, a geophysicist, brought along a device called a 'CTD', which stands 'Conductivity Temperature Depth'. It's getting referred to 'The Thing' or occasionally 'Suzie'. Whatever it's called, the long steel cylinder, which looks like some sort of nuclear device from a James Bond movie, has been getting dropped into the water from the bow of the Arctic Sunrise before the ship's windlass hauls back up the five of six hundred metres of rope that have followed it to the bottom of Petermann Fjord. The CTD measures not only 'Conductivity Temperature Depth', but also the 'turbidity' of the water, and gives details information about salinity and water currents.

More recently, Richard has gone all extreme on us, and had our helicopter, known as 'Lucky Bird', haul the CTD a few miles up the glacier to drop it into cracks and holes in the glacier itself, at what's become known as 'the whirlpool', a huge swirling vortex of blue water and ice chunks fed by melt streams running swiftly along the glacier.

Spending most of Tuesday at the whirlpool only increased my sense of Petermann's strange otherworldliness. I keep thinking of it as 'The Maelstrom', although Edgar Allen Poe's short story of the same takes place a long way from here, off the cost of Norway, near Lofoten.

At about 27km from the open sea and the Arctic Sunrise, around one-third of the way up the floating ice shelf, the whirlpool is fed by a ranging bright blue melt river that grows stronger as the sun grows higher in the sky. Richard estimated that by about 4pm on Tuesday, around 50 cubic metres per second were flowing past us, and vanishing into a hole in the ice.

This, of course, didn't stop him, with Eric's help, from dropping his CTD down 183 metres into the whirlpool, timing the drop to avoid the circulating ice blocks, and hoping that he would be able to retrieve the device again. When "Suzie" returned to the surface – and Richard later downloaded the data, it came up with some interesting data – at around 60m, the fresh water suddenly turned to saltwater. The ice under our feet could be thinner than we think.

Alun came back the next day with his radar equipment, which penetrates the ice and gives a view of what's below. His data matched Richard's, and lends credence to the fairly new revelation that warm ocean currents are playing a major role in triggering the acceleration, breakup and thinning of glaciers. Alun reckons that these currents are "are circulating around the fjord here and eroding the underbelly of Petermann Glacier at an incredible rate which is 25 times that of the surface melt".

As if all this wasn't enough, yesterday, when Richard, Alun, Faye, Sarah, Martin and others were at the whirlpool , a seal popped its head up several times to check them out – 27km from open sea!

Dave, Greenpeace International

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