Does going deep inside a volcano sound a bit crazy? Well, the volcano in question – Thrihnukagigur – hasn’t erupted for over 4000 years ago, and odds are pretty good that it will stay dormant for the foreseeable future. Nevertheless, this is a unique and absolutely mind-blowing experience – the feeling of being lowered down 120m on an open elevator (of the kind used to clean windows on skyskrapers) is quite intense, to say the least. The magma chamber is large and colourful, and walking around inside it feels more than a little bit surreal. The elevator set-up has only been present since 2012, when a National Geographic film crew needed to find a way to access the chamber. The volcano is within easy reach of Reykjavik, although obvious safety issues means you can’t visit it independently, and is an excellent choice for a half-day trip from the capital. But the trip does involve a one hour walk each way, and it can (given the usual Icelandic weather) be windy, wet and muddy.