They opened this ice tunnel in the last 5 years or so, to explore what these beasties look like from the inside. So far they look cold and dark and humid, requiring both waterproof suits and special crampons on your boots.
Still, better than the alternative. Wandering about on the glacier itself is extremely dangerous because of crevices and whatnot that may still be hidden by snow.
I know it’s artificial, but that doesn’t make it any less challenging. Tourists reading about this place and expecting a quick stroll from Reykjavik and back will be sorely disappointed. Even this somewhat tamed bit of nature must be approached with the utmost respect.