Prästens Badkar (The Priests Bathtub)

When thinking of a volcano, one probably envisions a giant mountain, with tufts of smoke rising from the top. This is not always the case however, especially if the volcano is created on a sandy beach and is also underwater. 

The Priest's Bathtub is the result of an artesian aquifer erupting millions of years ago. An artesian aquifer is a source of water that is trapped between two impenetrable layers of soil, like clay. This puts pressure on the source and if it mounts, the water will break through at the weakest point, spraying up and becoming a spring.

What makes this site so unique is that the spring also forced out a large amount of sand. This created a cone-shaped structure, which subsequently collapsed and fossilized into rock.

These types of natural creations exist worldwide, however, what makes this sand volcano such a wonder is that it's the only one found above water. For this reason, it has been studied by geologists and is a popular attraction for the small town of Vik. 

The name allegedly derives from a story that a priest once used the location to bathe. This is a bit hard to imagine however, as the shape of the structure makes it look great, but it doesn't appear to be very comfortable.