The rock is cool and smooth, shaped by millennia of fast-flowing water. Looking out through a convenient peephole, I see the gushing water falling powerfully a few feet away from me. I can feel a nimble in my chest. A fine mist covers my skin and clothes. We’re at Trummelbach Falls in Switzerland’s Lauterbrunnen Valley. Lauterbrunnen is also known as the valley of the 72 falls, and as we drive up from Interlaken, we can see some of them in the distance. But the one we’re visiting is unique. Trummelbach is a subterranean waterfall, Europe’s largest, a majority of it located inside a mountain. It’s accessed by a lift that takes visitors underground. One minute we’re standing in the bright sunshine of a European summer day, and the next, we’re shivering inside a dark cavern lit by lamps that cast eerie dancing shadows.

I can feel the water before I see it. A vibration runs through the rock, up through the soles of my shoes, and into my body. I can hear it too, a mad whooshing and churning all around us. Exiting the lift, I go on to a series of tunnels and narrow staircases cut into the rock, leading to platforms and lookouts that reveal the ten cascades of Triimmelbach Falls. Each offers a powerful sight: a cascade from above, the side view of a corkscrewr-shaped one, and the overwhelming volume of water of a third, as you stand below it. They carry the meltwaters of glaciers from around the Eiger, Monch, and Jungfrau mountains— nearly 20,000 litres every second.

Visitors halt to take photos, kneeling and bending in their attempt to capture the size of the falls. I hang back and linger, awed by the shapes and designs the water has wrought in the rock. I’m dazzled by the tenacity of little flowers and shrubs gripping these rocks, growing sturdily despite the fact that sunlight only trickles in through gaps and skylights. When we leave the mountain and emerge into the sunlight, I can still feel the cool mist clinging to my clothes, and the sight of the thunderous falls, clinging to my mind.