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
"The world-famous Reynisfjara shore, near the village Vik in Myrdalur on Iceland's South Coast, is widely regarded as the most impressive shore in Iceland.
Reynisfjara is a black pebble beach and features an amazing cliff of regular basalt columns resembling a a rocky step pyramid, which is called Gardar. Out in the sea are the spectaculary shaped basalt sea stacks Reynisdrangar.The area is rich birdlife, including puffins, fulmars and guillemots." https://guidetoiceland.is/travel-iceland/drive/reynisfjara