Reynisfjara is a beach of coal-black sand on the south coast of Iceland, under a cliff wall of basalt columns. The columns look like architecture. They rise at the back of the beach in tight tiers, mostly six-sided, and the lowest of them are low enough to sit on. They curve round the mouth of Hálsanefshellir, a shallow cave roofed by the same stone. Nothing here was built, and the sand was not washed in either. It is ground-down lava, black to the grain and still black when wet, swept down to the sea by floods from Katla, the volcano under the ice cap just inland. Katla goes off about twice a century, and this whole coast is what it has sent down.
The walk is the beach itself: flat black sand running towards the Reynisdrangar, with Mount Reynisfjall on one side of you and the open Atlantic on the other. The stacks stand out in the water, the tallest 66 metres, showing and disappearing as the mist moves. Icelanders say they are two trolls and their ship, caught by the sunrise as they hauled it towards land and turned to stone where they stood. In summer puffins nest on the green slopes of Reynisfjall and fly out over the sand, and on clear winter nights the aurora moves above the stacks. From high on the dry sand you can watch heavy swells burst against the basalt, loud enough and hard enough to shake the ground under you. There is no land between here and Antarctica, so the waves arrive with the whole ocean behind them. Every so often one runs far up the dry sand with no warning, and people have been pulled off this beach and drowned. A light at the entrance grades the waves before you walk out, and on red the columns and the cave are closed outright. Nobody who knows this beach ever stands with their back to the water.