"It's said to be one of the most unearthly places on earth and quite spectacular. Hverarönd is an area near Mývatn in the northeastern part of Iceland. The area has a lot of geothermal energy which shows itself in the form of bubbling pools of grey mud and sulphur. As a result of this the area smells rather strongly of sulphur but experiencing the almost alien-like landscape is well worth the smell." http://www.planiceland.com/vtours/myvatn_hverir/
Grjótagjá is a small cave that was formally used for bathing as it has a geothermal spring feeding it. However, the water became too hot to swim in and is now a photographic destination.
"Reynisdrangar are basalt sea stacks situated under the mountain Reynisfjall near the village Vík í Mýrdal, southern Iceland which is framed by a black sand beach that was ranked in 1991 as one of the ten most beautiful non-tropical beaches in the world. Legend says that the stacks originated when two trolls dragged a three-masted ship to land unsuccessfully and when daylight broke they became needles of rock." https://en.wikipedia.org/wiki/Reynisdrangar