From El Calafate our journey down to Tierra del Fuego took us south, back over the border into Chile to visit the Torres del Paine National Park. The park is known as one of the best in the whole of South America on account of its spectacular scenery and epic hiking trails. It has only recently acquired this reputation, as before 1959 it used to be one great big sheep farm, before being bought back by the Chilean government.

The nearest town to the National Park is Puerto Natales, a ramshackle collection of buildings that are really little more than shacks, stitched together from plyboard, corrugated iron and plaster, leaning against each other to keep out the cold. Dumped in the centre of town after a 6 hour bus ride we were a little unsure what to expect of our hostel, and were most pleasantly surprised when we arrived to find we had booked ourselves into a very well run B&B with warm rooms, TVs and big comfy beds.

We had no time to take a rest though, as we frantically ran around town trying to sort out our hiking trips for the next couple of days before the shops shut. Most people only stay in Puerto Natales for one night, heading off into the National Park the following morning to 'Hike the “W”' - a four day trek taking in the main sights in the park, camping en-route or in mountainside refugios. We neither had the time, equipment nor the inclination to put ourselves through that ordeal, so had to work out the best way to see as much as possible in the few days we had. After checking the weather forecast we decided to take the bus into the park the next day to hike one leg of 'The W' route – the most impressive stretch up to the namesake 'Torres del Paine' peaks – then take a rest day before taking on a one-day minibus tour of the other main sights.

At 7am the next day we clambered onto the bus taking us into the park. We slept most of the way to the base camp, waking up in time to be shoved off the bus at 10am, at which point we realised we had a 26km round trip ahead of us, and not that much time to do it in. Off we went! The first hour we walked along a broad flat plain, then up a mountain path that wound round into a steep river valley. There were a few dark clouds around, but for the most part the entire valley was lit up by the sun and we were soon down to wearing just our T-shirts. As we walked up into the river valley though, the weather flipped from nice to nasty. An icy wind kicked up and it started to rain and sleet. By the time we reached the first refugio at 12:30 we were soaked, freezing and thoroughly demoralised at the thought of another 10km ahead of us, mostly straight up, before we reached the end of the trail. To make matters worse the clouds had come in and the entire range was covered in a thick white mist, so we didn't even know if we would be able to see the Torres when we got there.

We sat in the refugio debating the best course of action over our soggy sandwiches. As we counted kilometres and looked out the window up at clouds, we found that we were sitting next to an English couple who were making the return trip from the Torres. They assured us that it was worth the trip, and as they had camped on the mountain the previous night before setting off at dawn, we felt like complete wimps for considering turning around halfway. So we set off again.

Luckily the weather cleared up almost as soon as we set off after lunch. The track was also a lot more easy-going and sheltered from the wind inside a shady forest. We kept up a good pace too, so found ourselves an hour ahead of our planned time as we broke free of the treeline and found ourselves at the foot of the final ascent. This last hour was to be a scramble straight up over a scree slope of boulders, sand and gravel. As Sarah has achieved true 'Mountain Goat Status' through our hikes in China, Borneo and Peru, we had no problems (well, maybe a couple of vertigo panics, but nothing serious). The view of the Torres del Paine when we reached the top of the scree slope was breathtaking. Three spires of granite laced with streaks of basalt, soaring above a hidden glacial lake you can only see when you reach the summit.

The way down actually took us longer than the way up, carefully treading down the mountainside till we reached the safety of the forest. The clouds rolled back in again, and we walked through more rain to make it back to the pick-up point with two hours to spare. To Sarah's disgust, I insisted we walk a further 7km back to an earlier drop-off point. She sulked for the first few kilometres, before I made the error of suggesting that the empty gravel road ahead looked like something out of a pop video: Cue Sarah's interpretation of 'That Don't Impress Me Much' by Shania Twain, followed by countless other karaoke classics, all the way home.

After a much needed rest day, lying in bed till noon massaging our aching legs and watching Friends re-runs, we were ready for another crack at the National Park. This time, we would be doing it from the comfort of a mini-bus with minimal hiking. It was a long day – over 12 hours of touring – but took us around all the sights we would have missed. We saw more mountains and glacial lakes, waterfalls, rheas (ostrich-like birds) with their chicks and lots of guanacos (another llama spin-off).

The two highlights for me though, were a trip to a giant milodon cave and a short walk to Lake Grey to see the glacier. Milodons were prehistoric plant-eating mammals that look kind of like giant sloths. They were about 10 feet tall, and were the preferred food of the hunter-gatherer tribes that used to inhabit the area. The first stop on our bus tour was an enormous cave hollowed out by an ancient sea, within which Victorian archeologists discovered a Milodon skeleton and human artifacts from around 5000 BC. The discovery of the Milodon skeleton caused quite a bit of excitement at the time – the Daily Mail even sent a team of explorers over in 1909 'To capture a live milodon to exhibit at London Zoo'. Ambitious.

Glacier Grey was the last stop of the day. We actually only caught glimpses of the glacier from the southern end of the lake, but the shore was crowded with massive icebergs that had broken off from the glacier and floated downstream with the wind. We nearly didn't make it to the lake itself as the wind blowing down from the glacier was so fierce - it regularly reaches over 100km/hr, knocking you off your feet and ripping the heat from your body. We definitely felt like we were close to the Antarctic, and were very glad once we had taken our photos and sprinted back to the bus. We were even more pleased as we sat back in our heated seats ahead of the rest of the group, and it started to pelt it down with rain, then snow.