Gluggafoss, also known as Merkjárfoss or Window Falls, is a stunning waterfall located along the Merkjá River. What makes Gluggafoss unique is its rock formation - the upper half of the cliff is made of palagonite or tuff rock, while the lower ledge is basalt. Over time, the river has carved tunnels and grooves through the soft rock, creating a series of "windows" in the tunnels. This is how Gluggafoss got its name! The waterfall even passes under a stone arch at the top. It's pretty cool, right? In the past, the waterfall went through some changes due to volcanic eruptions and ash deposits, but it has since returned to its former glory. So, if you're looking for a breathtaking natural wonder in South Iceland, Gluggafoss is definitely worth a visit!