I don't know if it was the relief of being on dry land or the excitement about being in Colombia - somewhere we had both really wanted to visit - but we were buzzing with happiness about being in Cartagena, and fell pretty quickly under its magic spell. It took a couple of days to get rid of our sealegs and to stop walking as if drunk (apart from when we had had too much rum), but that didn't stop us soaking up all that Cartagena had to offer.

During colonial times Cartagena was the most important bastion of Spain's empire overseas. It was (and is) a major port, and the treasure that used to be plundered from the local population by Spanish galleons was stored here until it could be shipped back to Spain, making the city a tempting target for attacks - the most famous being by Sir Francis Drake in the late 1500s, when he only agreed not to level the town when paid off with 10million pesos, which was shipped back to England. Sorry about that, Cartagena.

Cartagena's intoxicating mix of history, beautifully preserved colonial buildings and sweaty, salsa beat made it highly seductive. The hugely impressive walled town is surrounded by the old fortress walls (built to protect against said attacks) and within these walls are gorgeous, brightly-coloured colonial buildings, beautiful churches and convents, and shady plazas - it was just stunning, and every corner seemed to hold something even more gorgeous to feast our eyes on. Where we were staying in Getsemani, the outer walled town, was not as pristine but just as charming, with some great drinking/people-watching spots and cute little plazas and side streets tucked away. We could have easily stayed longer than five days there, enticed by both the city and its super-friendly inhabitants, but we decided to hotfoot it to Medellin, the sweltering heat being the only thing we were glad to leave behind in Cartagena.

Situated in a narrow valley, Medellin's cooler climate certainly provided a respite from the humidity of Cartagena. The country's second-biggest city is well-known for various things - railways, coffee, nightlife - though the most famous perhaps is its turbulent history thanks to Medellin's most (in)famous inhabitant, the drug warlord Pablo Escobar, who transformed the city into the capital of the world's cocaine business in the 1980s, making it once one of the most dangerous cities in the world. But as most 'paisas' (people from Medellin) will be quick to point out, Medellin is a very different place today, and there is much more to the city than the dark shadow cast by crime and cocaine. It was a great city to wander around, taking in the highs and lows of both the city's - and Colombia's - history, which we did mostly by means of a fantastic walking tour offered by a passionate and very knowledgeable local guide who gave us great insight into both the history of Medellin and Colombia, and the Colombian national psyche. A cable car up and over the valley hills gave us some amazing views of the whole city, as well as a bird's eye view of some of the city's 'colonias' (slums), with some of the poorer-looking homes seeming preciously close to slipping down the hill.

We then passed through a couple of very pretty colonial towns, the most impressive being Barichara, which was so beautifully preserved and pristine that it was hard to believe it was 300 years old. There we sampled the region's local delicacy, 'hormigas culonas' - literally, flat-bottomed ants - a traditional 'food' (?) dating back 500 years when the indigenous Guane people cultivated the ants for their supposed aphrodisiac and healing properties (they pretty much tasted as you expected: disgusting).

We were now on our way to the mountainous national park of El Cocuy, in eastern Colombia. We had a pit stop just outside the town of Sogamoso for a couple of days, by way of a warm up - the area had some beautiful treks, taking one high up into the Colombian 'páramo', a rare, glacier-formed tropical ecosystem that exists at altitudes of 3000-5000m, characterised by valleys, plains and mountain lakes. This ecosystem only exists in a few countries in the world, with a large portion in Colombia. We did a great day trek there, walking for around 8 hours from 2900m to around 4000m,accompanied by two dogs who followed us the whole way from the start point in town, the older one seeming to suffer from narcolepsy, as he kept lying down to fall asleep whenever we stopped, even if it was for a few minutes, and in the strangest of places and positions. It was a beautiful walk in the sunshine through the páramo, amongst all the 'frailejones' - a plant endemic to the páramo ecosystem, which looks like a cactus / pineapple hybrid, and with leaves as soft to touch as velvet. These grow about 1cm a year, meaning the ones we saw that were 3m high were 300 years old!

The altitude and (at times) challenging trek was good preparation for the peaks of El Cocuy, a spectacular mountain range forming the highest part of the Cordillera Oriental, the eastern part of the Colombian Andes formed by two mountain ranges. The Sierra Nevada del Cocuy has 21 peaks, three quarters of which are over 5000m. In 1977 a large part of the area was set aside to create the national park, however between 1985-2005 it was occupied mostly by ELN guerrillas, until the Colombian army moved in. The army has had a base in the mountains ever since and regularly patrol the trails (not that we ever saw them, apart from a few men in military uniform in the small town of El Cocuy at the bottom).

The stunning drive there from Sogamoso, through some very dramatic mountainous landscape, was very much indicative of what we would be facing, as was the attire of the locals in El Cocuy town, with their cowboy hats and woolly ponchos, the heat of Cartagena now a distant memory! We had a fantastic three days doing various day hikes, with a German couple we had met in El Cocuy town. The longest trek we did was around 9 hours (round trip), reaching almost 5000m, the highest altitude trekking either of us have done after our respective ascents to Everest Base Camp and Kilimanjaro. Luckily the altitude didn't seem to affect either of us too much, and while our German friends were far better equipped than we were, we didn't suffer too badly in our flimsy ponchos when the rain came higher up the mountain! The scenery was absolutely stunning, full of craggy peaks, glacial valleys and lakes, full of the now-familiar frailejones, and well worth the arduous climb and the shortness of breath. We stayed in a basic cabin at 4000m, which luckily had enough hot water and blankets (6 each) to ward off the cold, as because we weren't moving around as much it felt colder there than up in the mountains, even with every item of clothing on… but plenty of hot drinks served by the friendly owners kept away the worst of the cold, and the carb-overloading (potato broth for breakfast anyone?) helped power us through the day. On our last day we went from finishing a 6hour/22km walk back down the mountains to the town of El Cocuy, straight on to the night bus to Bogota, and as we stretched out our aching limbs on the comfortable reclining seats, it was no wonder we slept well on our first overnight bus journey of the trip!