Caving is an interesting hobby, if you don't suffer from claustrophobia. I don't, and believe me, I would have known if I did. It is one of the few activities that makes it possible to discover genuinely unexplored parts of the earth. That's far from routine, but when it happens it's worth the effort.

I have been caving since 1993, some years more and some less. Lately there has been little caving, it's not exactly a family sport (at least not until the kids grow up a bit). But I have been a few places, and brought home lots of pictures.

Some caves are very narrow and tight, and provide good training for tight-quarter rescue. The story of Pluto would not have happened without some of these trips

Råggejavreraige in northern Norway is the deepest cave in north Europe, and is well worth a visit

Caves are not the only thing underground, there are also mines. The old silver mines in Kongsberg can be visited horizontally, but if you really want to see them, you should take a vertical trip. Sadly, our caving club lost the concession there, but we run quite nice trips in the cobalt mines of Blaafarveværket instead. Such trips can look like this

My tour de force has been Castleguard cave. This 11-km linear cave in the Rocky Mountains of Canada is home to a (until recently) unclimbed aven. An aven is a vertical hole leading up; climbing avens can be easy or hard depending on their size, height, location and a myriad other factors. The 200-foot aven in Castleguard Cave was discovered in 1968, and measured with a hydrogen balloon and sewing thread. After that, it just sat there, daring anyone to climb it. Now, Castleguard Cave is not a place to be tackled lightly. Simply getting there is hard enough, with 20 km of winter/mountain skiing followed by a full day of hard cave travel to get to Camp One, with the aven another hour further in. When I stood open-mouthed at the bottom of the aven in 1994, I decided then and there that this would be my “lifetime project”. After a failed attempt in 1997 I succeeded in climbing it in 2005, much due to the unwavering support of my five teammates. Read all about it in my comprehensive, illustrated report

Castleguard would not qiute let me go, and when I got the chance to join a trip in Easter 2013 I did so - for once without a Great Project on my mind. This was a refreshing change; and the trip was made exrea special when it turned out that we might be saved the ski trip in.

The big gate that block unauthorized access also collects rocks coming out from the inside, during spring floods. Gather enough rocks and the whole thing will be broken by the irresistible force of the water. The deal offered by Parks Canada was simple: get rid of the rocks (several tons), and in return we'll fly you in! Of course we said Yes Please and had an unforgettable flight in. For the rest of that trip I felt like a real veteran on home ground, and spent my time sightseeing, filming (a new hobby) and meeting interesting people. The result can be seen on YouTube, with music by Kevin MacLeod of

Another side effect of Castleguard was meeting John Lay, who the following year offered me a place on the Push Team on his exploration of Thanksgiving Cave on Vancouver Island. This cave is also one of the longest in Canada, and still has potential. I'm still working on a definitive video, but you can already see some results on YouTube, as well as a collection of pictures.