The Lummelunda Cave hadn’t been explored more than 130 feet beyond the cave entrance until 1948, when three schoolboys discovered another, hidden entrance to what turned out to be one of the longest caverns in Sweden.
Every Sunday after that, the trio went to the cave and discovered more and more. They even used a boat to travel the river further and further into the tunnel. At one point in their journey, a large stone block fell from one of the walls, which widened an opening in the cliff.
The boys were curious to see what was inside, and when they walked into that opening, they discovered an unexplored passage that was 65 feet long and led to a large hall with beautiful stalactites hanging from the top. They called it “Bergakungens Sal,” which in English translates to “the Hall of the Mountain King.”
Today, this geological gem is a must-visit if you’re on the Swedish island of Gotland. Curious spelunkers can explore the cavernous hall and its astounding stalactites, and the more adventurous may take a boat ride on the river deep into the cave system, just like the three boys did years ago.