Lummelundagrottan
"The temperature inside was twelve degrees. Outside was thirty. The cave had been keeping that secret for ten thousand years."
I ducked into the cave entrance at Lummelunda on the hottest afternoon of my Gotland trip, when the outside temperature was nudging thirty degrees and the limestone alvar was shimmering in the heat. The temperature inside dropped to twelve degrees in about forty steps. A guide in a blue vest was explaining something about Silurian rock to a family of four, and I fell in behind them and let the cave close over me. It took my eyes a few minutes to adjust to the artificial lighting and my body a few more to stop expecting the heat to return.
Lummelundagrottan is about three kilometers of accessible passages carved through Gotland’s limestone by an underground stream over millions of years. The Lummelunda river still runs through the lower sections of the cave — you can hear it in the deeper chambers before you can see it, a low gurgling presence that appears and disappears as the passage widens and narrows. The formations are extraordinary: stalactites hanging like chandeliers from the ceiling, stalagmites rising from the cave floor in shapes that suggest organic things, cave coral on the walls in white and cream and the faintest trace of pink. The guides light the formations theatrically, in amber and gold, which is either kitsch or genuinely beautiful depending on your mood. I found myself thinking it was both.
The cave was first properly mapped in 1948, though locals had known about sections of it for much longer. The passages are well-maintained and properly lit, with wooden walkways through the wetter sections and metal staircases between levels. It is not a wild cave experience — there are no crawling passages or helmet lamps required — but the scale of it is larger than you expect walking in, and the silence in the deeper chambers is complete. I paused at one point when the guide had moved ahead and stood in the absolute quiet, and the darkness at the edge of the lit zone was not threatening but geological — old in a way that eight hundred years of Visby’s walls are not.
Upstairs, back in the heat, there is a café and a small geological museum that I did not read closely enough but should have. The stream that carved the cave still emerges into daylight in a wooded valley below the entrance, and I walked down to it and sat on a rock in the shade and ate a piece of cake from the café and thought about what the cave was doing when no one was looking — which is the same thing it had always been doing: filling up slowly with stone, drop by mineral drop, column by column, at a pace that makes the word patient feel inadequate.
When to go: The cave is open from May through October, with the busiest visits in July when the combination of summer heat and cool cave makes it especially appealing. It is an excellent mid-day stop on the main road north between Visby and the Fårö ferry, roughly 13 kilometers from Visby. The cave temperature stays at a constant twelve degrees year-round; bring a layer regardless of the season outside.