Thrihnukagigur Volcano, located near Reykjavík, Iceland, is a dormant volcano that hasn't erupted in over 4000 years. Discovered in 1974, it's unique because visitors can actually take an elevator down into its magma chamber, which is pretty cool! In 2015, the Icelandic band Kaleo even recorded a live performance inside the volcano. It's definitely a must-see for adventurous travelers looking for a one-of-a-kind experience in Iceland.