Take a journey towards the centre of the earth and explore the inside of Thrihnukagigur volcano. This is a very special experience and adventurous, it starts with a 50-minute hike to get to the crater and then you need some guts before you descend 120 meters (394 feet) to the bottom of the crater in an open elevator. The volcano last erupted over 4000 years ago so no need to worry about that, just enjoy the journey! There are three craters which are prominent landmarks but you will be descending into one of those, and this is where the volcano draws its unpronounceable name from. The volcano is only about 20 km (12 miles) from Reykjavik. You should bring good walking shoes as well as warm clothing, and definitely do not forget your camera!
The Silfra is undoubtedly one of the most fascinating and adventurous places to dive on Earth. The fissure is located in Thingvellir National Park, which is on the UNESCO World Heritage Site, both for its historical and cultural significance as well as natural and geological uniqueness. The Silfra is a special place mostly as the dive allows you to touch both North American and Eurasian continents at the same time, as the crack is located between the two. It is the only place in the world you can dive and do that. The visibility there is also incomparable with over 100 metres (328 feet) visibility, the reason is the cold glacial water and that it is filtered through underground lava for 30-100 years before it reaches Thingvellir lake. You can even drink the water while you dive if you feel thirsty!
Vatnajökull is an enormous glacier with breathtaking landscape. Why not enjoy that landscape on a snowmobile on proper speed. From the National Park which the glacier is located in you can also see waterfalls, volcanic activity, cliffs, broad wetlands, geothermal activity and crater plugs. Whilst there you could take a look into the ice cave located on Vatnajökull glacier for a full adventurous day! Though most tourist companies offer necessary equipment for the trips, it is essential to wrap warm on the glacier, as it gets really cold, and to follow all advice from the professionals. The glacier is magnificent but it has cracks that the traveller needs to be aware of.