For some years, Rene at Noma has been telling me about a mad Scotsman called Roderick Sloan who lives up in the Arctic Circle in northern Norway and supplies his restaurant with, among other things, the most amazing sea urchins.

Now, sea urchins happen to be my most favourite thing to eat in all the world, ahead even of flødebolle so, when I finally got to meet Roderick at the Mad Foodcamp Symposium back in the summer and he invited me up to Nordskott where he lives and fishes, I said yes in a heartbeat.

It was staggeringly beautiful, despite being -15.

Roderick had also invited a bunch of chefs, not just from Noma, but also from elsewhere in Norway as well as the much acclaimed Faviken in Sweden. Here he is, telling us where we are.

Cognitive scientists tell us that we more easily agree to do something arduous if it is going to happen far in the future. I don't really do boats. When Roderick invited me to the Arctic to go fishing in February, it was August. I said yes all too readily, then spent the next seven months wondering what on earth I had gotten myself into.

But here I am with my quarry after a not-too-bad-at-all trip on a trawler (admittedly drugged up to my eyeballs on sea sickness tablets).

But Roderick didn't just have a little fishing trip in mind. He wanted me – and in particular the chefs he supplies – to really understand exactly what was involved in the harvesting of the seafood they served in their restaurants. So, he gave us some dry suits (though no gloves or hats), a snorkel and sent us into the -2 Arctic waters to get a feel for ourselves.

The dry suits kept us reasonably warm (I was fully clothed beneath this, which explains the 'tubbiness'), but by the time we came out of the water it literally felt as if our hands were on fire, an incredible sensation – so cold, it was hot.

Roderick also dives for mahogany clams (left) and soft shell clams (right), or as the latter are apparently nicknamed in the Noma kitchen, 'dick clams'. Can't think why.

The dick clams, which we ate raw after peeling the, erm, protrusion of its elephantine skin, were the sweetest seafood I have ever eaten, with a wonderful texture. Fantastic.

The mahogany clams were also sensationally good, here being prepared by Jonny of Faviken, and served on flaxseed crackers. A stunning combination of earthy and iodine flavours. New Nordic surf 'n' turf.

The money shot:

Why the starfish? Well, as Roderick explained, every time a restaurant asks him to send a sample box he includes a couple of them. He knows they are eaten in Japan, and they are related to sea urchins, but can't figure out how to prepare them and he is hoping some inventive chef will come up with a use for them (I think in Japan they dry and grind them as a seasoning, though I am not sure).

Sea urchins have had a tough time of it these last years. Off the coast of California they were considered a pest as they were believed to eat the kelp which local companies used for beauty products, so they covered them with caustic soda. Then they realised they could eat them or sell them to the Japanese to eat, so they over fished them. The only really sustainable way to harvest them is how Roderick does it – leaving fields alone on a five year rotation so that depleted stocks have a chance to regroup – and picking them by hand.

It's hard work, and I watched Roderick dive for about an hour, as he lost all feeling in his lips, and his hands turned to blocks of ice during the process, but I am glad someone's doing it. And I am sure the guys at Noma are. Here is their 'sea shore' dish which features Roderick's sea urchins as a powder strewn like sand across the pebbles.