While recent scientific research1 suggests the columns were formed as a natural consequence of lava cooling, legend has it that the giant Finn MacCumhaill (Finn McCool) built the causeway to walk to Scotland without having to get his feet wet.
1 Jagla, E. A., Rojo, A. G. Sequential fragmentation: the origin of columnar quasihexagonal patterns. Physical Review E, 65, 026203, (2002) [1]References