Scientists have attached satellite tags to eight walruses off the west coast of Greenland. They hope to solve the mystery of where the hefty creatures migrate over the summer months.
Our science reporter joined the research team on its expedition.
MONDAY 16 APRIL: GOODBYE GREENLAND
The time has now come to say farewell to Greenland.
Getting a taste of life here, both on sea and on land, has been a privilege, as has been getting to know Mikkel, the trawler's crew: Knud, Ole and Gustav, as well as the other friends I have made along the way.
A job well done
And, of course, there were the walruses. My close encounter with the tusked giants was possibly one of the coldest, scariest but most exhilarating experiences I have ever had.
As I return home to warm up a bit, the baton is now handed over to the "wallies" who begin their migration to who knows where. I'm very much looking forward to seeing what these magnificent animals get up to over the next few months.
SATURDAY 14 APRIL: BACK ON DRY LAND
A couple of days ago, the team and I returned to Sisimiut's harbour jubilant with the walrus tagging success.
It felt as if we had been at sea forever and setting foot back on to dry land was a strange experience - I suffered a sort of reverse sea sickness as my body was, by now, very much used to reacting to the pitches and swells of the sea rather than the static ground.
A tupilaq was once used by witch doctors
The few days' delay before I can get on to a flight back to the UK has given me the opportunity to see the crew in another setting.
At sea, they worked incredibly hard all of the time, often from 6am through to midnight without a break. So seeing skipper Knud Lennart relaxing in his beautiful home, when Mikkel and I were invited around for some very delicious roast musk ox, felt very much out of the ordinary.
And visiting deck-hand Ole Lennart, his wife Marie and grandson Kim in his home gave me a chance to talk more to him about his experiences in the town.
Life had changed a lot and very fast since he grew up here in the 1950s, he said, the population had exploded from just a few hundred people to 6,000.
But tradition in Greenland remained strong, his grandson Kim translated for me.
Ole and his family told me more about greenlandic culture
I was shown intricate Greenlandic costumes, stitched out of seal skin and fur by Ole's wife. And on proud display throughout the house were symbols of Inuit culture - beautifully crafted model kayaks and harpoons, ancient walrus tusks that had been found on the shore, a mounted seal's head, and a tupilaq - a carving once used by witch-doctors.
The visit made me think about what life must have been like here years ago.
As someone used to living with every conceivable modern convenience, I find it hard to imagine how people could not only have survived, but thrived, in this harsh climate.
Greenlandic people are very proud of their culture, explained Ole, and it is important that it is kept alive.
WEDNESDAY 11 APRIL: WALRUS JACKPOT
After five days of waiting and waiting, we finally hit the walrus jackpot.
On Tuesday morning, we awoke to find that a strong wind had broken up some of the sea ice, allowing the skipper to navigate the boat to a bank where walruses often go to feed.
Soon after we got there, a closer look at a brown blob far off on the horizon revealed it to be a walrus.
Layers of clothing were thrown on, and researcher Mikkel, crew-member Ole and I jumped into a skiff that the trawler had been carrying throughout its journey.
The smaller vessel meant we were able to sneak up on the animal as it lay snoozing on a hunk of ice, but it heard us as we cracked through the frozen water and promptly slid into the sea.
A chase ensued - the walrus would pop its head up a few tens of metres away to breathe in some air, someone would spot it, yell, and the boat would race towards it, arriving just as it dived back under again.
Keeping watch for walruses paid dividends after five days
This happened a few times until we finally got lucky and arrived just as the walrus came up.
A quick "thwunk" from the crossbow and the satellite tag was attached to the animal's shoulder.
Even though I had been assured that the tags wouldn't hurt the walruses because of their tough skin and thick layer of blubber, I was still relieved to see that the animal barely seemed to notice the tag as it landed on its hide.
As we were celebrating, another cry of walrus went up, and soon the animals were being tagged left, right and centre; some with the crossbow, some with the CO2-powered gun and others with a harpoon that Knud, our skipper, had crafted. After days of nothing, seven walruses had been tagged in just a few hours.
And today turned out to be just as action packed. Unfortunately two of the tags were lost - they skimmed on the water just before they hit the walruses, sinking to the bottom of the sea, but another one, launched by Ole with the harpoon, hit a walrus squarely between the shoulders - the perfect place for a sat-tag.
A success rate of eight out of 10 tags was "pretty good going", Mikkel concluded.
The satellite tags were about the same size as a lighter
And what of the walruses? Well, I knew they were going to be huge, but I didn't realise quite how big they were going to be, especially when you are only a couple of metres away from them in a puny boat.
I suddenly realised that if there was to be a tussle between walrus and skiff, walrus would very definitely win.
But I also found them rather lovely - their faces with tusks and whiskers were just so full of character, and they were sociable too, often swimming around in groups of two, looking much more graceful in the sea than when on the ice.
I was a bit unsure about what I'd make of them before I came out here but, I have to admit, I'm a walrus convert.
MONDAY 9 APRIL: FOOD IS FUEL
While I've been on board, waiting for a walrus to appear, I've been getting to know the crew better and learn a little about Greenlandic life.
Gustav, one of the deck-hands, spoke to me about how important hunting was to the Inuit population.
He told me how his grandfather lived off the land, hunting seal, reindeer, whales and walruses for food and also to make clothing and tools.
Gustav says hunting is vital for the Inuit people
He said that hunting was still important for the local population.
Many goods are imported from Europe, he explained, making them extremely expensive. For some locals, hunting was still necessary to get the food and clothing they needed to survive the harsh conditions, he told me.
I've also had the chance to experience some traditional Greenlandic dishes here on the boat.
In the colder-than-a-freezer temperatures, food really is fuel. The body burns up a lot of calories just trying to keep warm; so rich, meaty stews are a regular feature on the menu on the boat.
Last night, I tried reindeer - putting any thoughts of Rudolph and his red nose to the back of my mind. Mikkel told me that it was a nutritious, tasty meat - and it's cheap too, since it doesn't have to be imported. It was soft - tasting somewhat like beef, but better.
And then I found out the other steaming pot next to it was seal meat. Earlier that day, a boat had pulled up next to ours with a bloody bag sat upon the deck - I didn't really think much of it at the time, but now I suddenly understood that the bag had contained my dinner.
Seal meat is tasty, nutritious and cheap, says Mikkel
Innards, blood, blubber and meat had been boiled up into a very rich stew - the crew looked at me with anticipation as they spooned some of it into my bowl.
The meat was almost black in colour, a little chewy and both fishy and meaty in taste.
But the thing I really noticed was how warm it was making me feel - my face turned red and my toes were glowing - and even though I'm having problems getting the images of cute pinnipeds out of my mind, I can understand why this sort of food is important in a territory like this.
SUNDAY 8 APRIL: WAITING FOR WALLY
It's all about the ice, here at sea.
You need enough of the frozen stuff so that the walruses can laze about on it after dining on a feast of clams and other molluscs, but not so much - as has been the case so far - that it is impossible to get to the Arctic animals.
"Ice, ice... too much ice," has been something our skipper has been saying rather regularly over the last few days.
A crew member used an orange to practise his tagging technique
We have been trying to reach the shallow banks where the "wallys", as Mikkel calls them, go to feed.
But so far, we have only been able to skirt around their edges, every so often finding a break between the thick layers of frozen water to steer through, all the time with huge icebergs drifting around.
Still, a couple of "walrus" cries have been sounded by the beady-eyed crew, who spend the hours scanning the white horizon for the tusked creatures as the trawler crunches through the icy water.
I've got the routine down pat now.
The slightest sniff of a walrus means you have to rush into the galley, throw on your Michelin-man-like flotation suit over the four layers you are already wearing, then the extra socks and snow boots go on, followed by balaclava, neck gaiter, hat, gloves and mittens.
Then we rush outside. Mikkel grabs his crossbow and satellite tag on the way, and climbs up the ice-covered ladder on to the deck.
The boat has been hemmed in by the ice
And then we wait, and wait, and wait in the hope that the walrus might reappear, all the time standing in the -25C temperatures while a strong wind slaps the freezing air on to your face.
I hadn't really thought a 1.5-tonne beast could be described as wily, but so far, that's exactly what these walruses have been!
Some days have been so icy we haven't even been able to move from the cove where we have been spending the night.
But the spare time has given Mikkel the chance to rehearse his walrus tagging skills.
I was amazed to see the crew fearlessly clamber on to the sea ice to set down an orange for him to fire a dummy sat tag at from his CO2-powered gun (which he had brought along in addition to the crossbow).
After a few shots, he told me he was ready to swap fruit for walruses - should we ever get close enough...
THURSDAY 5 APRIL: TURNING GREEN
Before I left the UK, just about everyone I told about the walrus trip asked me what my sea legs were like.
I had to give the honest answer that I didn't have a clue as I'd never been sailing before.
View from the boat, heading west from Sisimiut
Armed with plenty of sea sickness pills - just in case - I boarded the Nanna L trawler (named after Knud's daughter). And as we left Sisimiut, heading west, I soon discovered that my sea legs were a little shaky.
A plastic bag quickly became my accessory of choice as I sat staring at the horizon turning an icky shade of green.
But I'm pleased to say that the bag never got used - and a few hours into the trip as we approached the calmer, ice-covered waters, I began to feel just about normal.
With me on board are Mikkel, chief walrus tagger; Knud the skipper; and his two deckhands, Ole and Gustav. The boat and crew are usually at sea fishing the Arctic waters for prawns, but Gustav told me it made a nice change to look for walruses.
The day was spent scanning the water for signs of the tusked beasts, both from the bridge, and also from the deck of the boat.
Gustav and Ole would regularly clamber on to the slippery deck to survey the ice for a clearer view of any creatures, braving the -25C temperatures outside.
Temperatures were -25C on deck
I joined them for a while. With the wind helping along the freezing conditions, it is safe to say that it really was ridiculously cold out there - and I soon had to go back in to defrost.
The day was not to provide us with a walrus sighting - a glimpse of a bearded seal off in the distance was the closest we got.
WEDNESDAY 4 APRIL: DOWN WITH THE DOGS
Mikkel and I met the boat's skipper Knud Lennert this afternoon. He knows these icy waters very well, having spent the last 20 years navigating them.
He thinks we may be able to leave the port tomorrow morning, but warned that it is going to get cold out at sea - and for a local to have said this means it is going to be really, really freezing.
Nanna says Sisimiut is a place where everybody knows everybody
Knud's 18-year-old daughter Nanna joined us to translate some of the information for me. The Greenlandic ski champion recently spent a year in New Zealand perfecting her English.
She asked me if I wanted to join her and her younger brother on a dog sleigh ride - and who could refuse such an offer?
No place like home
Nine beautiful huskies pulled us over the hilly terrain, crossing frozen lakes covered with snow that had fallen the night before.
The sleigh was covered with a reindeer hide, making a snug, warm seat to sit on as we were whisked around at some pretty scary speeds.
Huskies whisk the sleighs along at fast speeds
During the journey, Nanna told me about Sisimiut. About 5,000 people lived there, she explained, making it the second largest town in Greenland. It was the kind of place where everybody knew everybody, she said.
Nanna said that although she had a great desire for travel and adventure - like many Greenlandic people - she loved her home very much.
I'm sad to be leaving Sisimiut after such a short stay - it truly is beautiful here, but my boat and the walruses await.
WEDNESDAY 4 APRIL: WALRUS FOR SALE
This morning, I got the chance to don my thermals and go out and explore the town.
With me was Mikkel Villum Jensen who is leading the walrus expedition. After weeks of talking to him on the phone in preparation for the trip, it was good to finally meet in person.
BBC NEWS - WALRUS WATCH
Up to 10 walruses to be tagged
Location data fed to Denmark
BBC News to map positions
It soon became apparent that walruses are prominent in Sisimiut. They feature on the town's flag, some of the pretty buildings are painted with pictures of them - and walrus meat is also for sale.
We walked (or rather, Mikkel walked, I slipped and fell) up the steep hill to the shop where local fishermen and hunters sell their wares.
Behind the counter lay slabs of deep-red, fatty meat on sale for 40 Danish Kroner (about £3.50) a kilo.
Erik, the shop-owner, told me that the meat was popular in Sisimiut and it was "very tasty". About seven walruses had been killed for meat this winter, he explained.
Shop-owner Erik said walrus meat was very tasty.
He said that Greenlandic people had eaten walrus meat for many years, along with reindeer, seal and musk ox, and it was a strong part of their tradition.
Walrus meat and skin were also fed to the huskies, he added, as a protein rich meal for the working dogs.
TUESDAY 3 APRIL: A SHAKY START
Getting to Sisimiut - the port in west Greenland where the walrus tracking trawler is to set sail - was supposed to be the easy part of my trip.
Fly to Copenhagen from London, jump on the flight to Kangerlussuaq, a former US army base in central Greenland, then a 10-minute wait before the short connecting flight to my final destination.
Or so I thought. The 10 minutes quickly turned into hours, before, eventually, the dreaded "Your flight to Sisimiut has been cancelled" call came over the tannoy, followed swiftly by an even more fearsome "and there will be no more flights there today".
I soon learnt, after finding some kind companions - Morten and Vivian - to share my waiting time with, that delays are common in this part of the world. Planes are at the whim of the weather, which can turn at any second. There was nothing I could do, they said, but sit and wait it out.
But today, after a night spent in some old army barracks, the weather settled and I could continue my journey.
The flight to Sisimiut was breathtaking. The window of the tiny plane revealed a mountainous snow-covered landscape studded with bright blue fjords.
Boats in Sisimiut harbour are waiting for good weather
And the town itself was also stunning. Small houses, painted in primary colours, nestle in the snowy hillside, overlooking a harbour below packed with fishing boats bobbing amongst the ice.
I have a few days to wait until the weather is deemed good enough to set sail - and in the meantime, I can't wait to brave the -10C temperatures to go and explore.
It is not clear whether the Laptev walrus is a separate subspecies
The tagging study is being run by the Greenland Institute of Natural Resources, in cooperation with the Danish National Environmental Research Institute and the Technical University of Denmark.