Yesterday, on the way back from Landmannalaugar, we discussed the wind. There are two experimental windmills up - experimental since it can get windy in Iceland. The guide told us that Hurricane Sandy had winds of about 48 m/s. Shortly after that, there were storms in Iceland too, in which at one point the wind on the highland road was measured at 70 m/s but generally, their storms are around 25 m/s. Icelanders, by the way, are very precise about everything.

With this fresh in my mind, it was stormy last night. I spent a lot of the night awake and fearing for the roof or the lamp post across the road or convinced I was going to get up and find Reykjavík destroyed. At 6.30 I had to get up to stare out into the darkness and see how bad it was. Of course, strong winds are nothing here and of course they didn't cause a problem.

I got my hot chocolate and waited on the street corner as usual for my pick-up, this time in a minibus. We did a quick pick-up tour of Reykjavík, finishing up with eight people - three British, one Londoner now living in New York, three New Yorkers and a man from New Zealand now living in Germany. I don't know what it is bringing people from New York to Iceland at the moment - perhaps it's because of the warmer weather here.

Because Tolkien borrowed a lot of his names - the dwarf names especially - from Norse mythology, it's not unknown to come across someone who shares their name with someone from Middle Earth. Our guide today was Dóri, who was not a dwarf but he was armed with an axe and a spectacular beard. Dóri is an Icelandic name I can more or less manage but just to be extra helpful, he had it embroidered on his fleece. What was particularly odd, though, was that he had exactly the same accent as Kermit.

We took the Ring Road down to Hvolsvöllur. That's about an hour and a half and I've done that bit of road so many times that it's tedious. Up past the power station, down to Hveragerði, through Selfoss, keep going through the farm land until you come to the last stop before glacier world. We stopped at Hvolsvöllur to stock up and then kept following the road for another 45 minutes to the turning to Sólheimasjökull - the Home of the Sun glacier. It's a glacial tongue coming down from Mýrdalsojökull and I visited it with Reykjavík Excursions in October, walking underneath magnificent ice caves. These are now gone. The glacier is creeping down at about 5-15 cm every day but it's melting faster than it's moving.

We were fitted for crampons, given ice axes and harnesses, got into our waterproofs and put on helmets and trekked over to the edge of the ice where we had to put on the crampons. They made it seem a lot harder last time. This time, while we were doing that, some tourists who'd come up on their own, presumably, decided it would be a great idea to wander around in normal boots on the ice, just metres away from what looked like a very deep crevasse. I don't think anyone in our group agreed with this idea.

We started our climb. It's quite awkward because the end of the glacier is just a mess of crevasses and gravel and ash from Eyjafjallajökull (or E15 as Dóri calls it, presumably because there are 15 letters after the E) and you have to keep hopping from ice back to what looks like solid ground. It isn't solid ground. There's ice underneath, it's just that the layer of gravel and ash is thick enough that you can't really tell.

Once we were up onto the glacier, we were introduced to moulins and crevasses. The moulins are the nasty ones - they're vertical tubes in the ice where water rushes down. The biggest one in the world, in Greenland, is 2km deep and the bowl at the top of it is 50 or 60km in diameter - or deep enough to scream three or four times before you reach the bottom. The biggest one Dóri knows about in Sólheimasjökull is about 200m deep. Several of the ones we came across were deceptively small, ranging from about the size of my hand to smallish bathtub size ones. You don't want to fall in any of them.

We kept climbing, stopping every now and then for another glaciology lesson. The glacier was striped with blue and white ice. The blue ice is about 7% air, compared to the 20% or so air in the white ice and a blue and white together represent one year. In the winter there's lots of snow so it gets compressed and the air squeezed out and that forms a blue layer and in the summer, there's less snow, it's not as heavy, it's a bit puffier, it forms a white layer. Repeat over and over again. It apparently takes about 10 metres of snow to create 1cm of blue ice and the blue ice is absolutely crystal clear. A bit weird to walk on because you can see through the ground. The glacier twists a bit because of where it's hit the mountains on the way down, so the stripes are vertical in some places and horizontal in others. Then we discussed the local volcanoes, that is E15 and Katla. Dóri was detailing exactly what will happen when Katla erupts. The flash flood will be colossal. Easily big enough to just pick up the 8km-long glacier we were walking on and fling it into the ocean a few miles away, easily strong enough to punch a hole through the mountains, will wipe out a few farms, etc. Katla is overdue. Have I mentioned that recently? Dóri also explained glaciers as Snickers bars. The chocolate is the thin, tough layer we're walking on. Below that is a thick layer of softer, fudge-like ice and below that - like the caramel, but on the bottom. Ooh! Or like a Snickers bar turned upside down! (as he put it, very excitedly) is the melted water that lubricates the whole thing and makes it slide down the valley. And in the middle somewhere, there are nuts, or in this case boulders and lumps of rock taken from the mountains on each side. In this analogy, I guess the volcanic ash doesn't exist.

We kept on climbing, now walking across horizontal layers of blue and white ice, each about a foot thick, towards our ice climbing wall. It was more or less a perfect wall, stripy, about 15 feet high. Dóri scrambled up the slope to rig the wall while the rest of us made ourselves comfortable. Some of us settled down on the floor and Emily from New York managed to slide down and crash into me crampons first. It didn't hurt too much. Then Dóri decided the best way to come back to us and simultaneously teach us the basics was to abseil down the sheer stripy wall. He was in the middle of explaining how to use the axes when Paul from New York from London fell over spectacularly, slid down the slope backwards and nearly took us all out like skittles. The instruction was paused while he was rescued from the ice.

While Dóri was rigging the thing, the rest of us had been discussing it and I'd told Emily what I'd seem in pictures. Now we discovered that I'd been pretty much right - you stab the wall with the spikes sticking out of your toes, rather than trying to grip with the sole of your feet like you normally would. I'm rapidly coming to the conclusion that everything to do with ice and snow is completely counterintuitive. We had a try one at a time, borrowing each other as bagholders, axe holders and photographers.

The climbing axes are different to the walking axes. They're shorter and curved and the blades curve down like hooks, and they have better grips on the handles. You reach up above your head and chop at the ice until you get the blade hooked in, and it's only the very tip of it. Then you kick your toes in and use that to stand on. At first I did ok with my feet. I was struggling to chop axe-holds and kept hearing "Great footwork!" from below but once I got halfway past the wall, I started to get tired. My legs were shaking - we'd already had that with Emily, Dóri calls it Elvis and he commented that Elvis lives on in more than one person. I think for the last five steps up, my weight was on the rope more than it was on my feet or axes. The axes kept slipping, I couldn't chop as well with my left hand as with my right, my right foot didn't want to stay pegged into the ice and I was trembling. The top was just above me, just out of reach. I hooked an axe in again, managed to hoist myself up another step and heard Dóri say that if I reached up with my axe and touched the carabiner, I'd be at the top. I scrambled for that carabiner. I was sliding my hand further and further down the axe to make it stretch just half an inch higher.

Getting down again was easier. The others had had to have step-by-step instructions while on the wall on how to abseil but I'm very used to that and I walked myself down the wall easily enough for Dóri to observe that I'd done it before. I slightly overdid it - to give myself enough slack to undo the rope I abseiled right down to the ground and then was too exhausted and trembling to get up. The ice axes had to come back out to haul myself to my feet.

Sitting on the ice afterwards, comfortable on the ground without slipping or sliding anywhere drinking hot chocolate and waiting for my hands to stop shaking was a little bit blissful.

Once everyone had had their turn at climbing, we had to go back up out of our little bowl, onto the top of the glacier and walk down. Walking down is harder than up on crampons and two of our New Yorkers needed Dóri's hand most of the way down.

It had been damp and windy earlier but now the sun had come out, just in time to start setting. The lagoon at the bottom is very brown but it's also very reflective and came in handy for a lot of photos. There's a waterfall coming down the mountain opposite and Dóri said he hadn't seen it this powerful this time of year for a long time. We walked on before he added "Something big is coming" which is a slightly disturbing thing to hear from someone with the same name as a character from The Hobbit. All he meant was that probably the really cold weather is still to come, since 5° and no snow on the ground is not normal for an Icelandic January.

We got out of the crampons and harnesses and helmets and returned the axes and then, as we got back in the minibus, we were presented with our packed lunches. I enjoyed the apple juice but instead of the ham and salad sandwich, I made my own rolls from my bread and my indestructible cheese slices (just about the only food improved by being left on a glacier). I also left the chocolate doughnut for the time being.

The last stop before we got back was Skógarfoss, or possibly Skógafoss. The guide books and leaflets are very inconsistent on whether or not there's an R in it. Just as I've decided which spelling is correct, I find it written completely differently elsewhere. Anyway, we stopped there, just for fifteen minutes which just isn't enough for this waterfall. It's pretty big and pretty powerful and only two of us were brave/stupid enough to try and get up close - me, obviously and Daniel from Germany from New Zealand. We borrowed each other's cameras and got right into the spray for the pictures and in the thirty or so seconds it took, even with waterproofs on, we got drenched. Then there was a toilet stop, which I used to take photos of the waterfall with its reflection in a puddle - Dóri had talked about this puddle earlier and then paused the minibus by the puddle to point it out as we drove to the waterfall. So I obediently stopped and took photos of the waterfall and its reflection and the surrounding mountains and their reflections and the spectacular sunset behind us.

The problem with getting so close up to the waterfall was that I then had to spend two hours on a minibus driving back quite damp and quite cold. It was great fun at the time, I was grinning like a loon when I came back to the minibus but a few miles later, not so funny. Dóri estimated it was 2hrs 15mins back to Reykjavík but since people had a Northern Lights tour picking up at 7.30, he'd try to make that two hours. I know roughly the timings on that road - it's 40 minutes to Hveragerði then 10 minutes to Selfoss, so if we made Selfoss by 6.10 we could be home by 7.

We did it a bit quicker. The whole journey in 1hr 35 mins, actually. I spent part of the journey asleep, part of the journey trying to decide whether or not to get some more bread this evening and part of the journey trying to work out how to get rid of that sandwich. I decided not to get bread - I was tired and a little bit achy and pretty cold by the time we got back, my boots were soaked yet again and I wanted to get in, get dry socks on, get changed and fall on my bed. Which is exactly what I did. First job once that was done was to download my GPS data and then I ate my chocolate doughnut. I've never eaten a doughnut in my life and although it was edible, I'm not entirely convinced and I probably won't bother having another one.

Tomorrow is "Riding & Wellness" - that is, a couple of hours on an Icelandic horse, followed by a trip to Fontana Spa. This one's different from the Blue Lagoon. It's built on the side of a lake, directly over the coolest of three hot springs, so all the heat and the water is coming right out of the ground right there instead of coming as waste from the power station into a pool dug out of the lava. There seem to be baths of varying temperatures, a bit of geothermal beach and you can even dip in the lake if you want, although I gather the lake is not hot. Then we stop at Þingvellir, the Parliament Plains, one of my favourite places in Iceland, on the way back.