Svartifoss was one of those memorable waterfalls thanks to hanging hexagonal basalt columns underlying it. While basalt columns aren't anything new around waterfalls nor is this waterfall very big (it's only 20m tall), it seems that the basalt columns on this waterfall are very pronounced. Besides, we were able to get real close to the falls and give ourselves a bit of a geology lesson by examining how geometrical the columns were (from the pieces that have chunked off and piled up at the base).