Kvernufoss is a secret that most visitors to Skógar walk straight past. Just fifteen minutes' walk east of Skógafoss, along a path that most people miss entirely, this 30-metre waterfall drops into a narrow canyon where you can walk behind the curtain of water on a wet ledge of rock. In summer, when Skógafoss is surrounded by hundreds of people, Kvernufoss is typically visited by a handful.
The path begins behind the Skogar Folk Museum and follows the river upstream through a gorge of basalt columns. The walk is not difficult but the final approach involves some scrambling on wet rock — good footwear with grip is necessary. The reward is an enclosed, genuinely wild-feeling waterfall that you can enter and stand behind. This is one of the better kept secrets on Iceland's south coast.