Like the peaks of submerged mountains, these almost barren rocks stand some 16km offshore in the Atlantic. The smallest, Little Skellig (not accessible), is a nature reserve teeming with puffins and gannets. The largest, Skellig Michael, is the where St Fenian founded a monastery in the 6C. Its well-preserved ruins (a church, two oratories and six hive-shaped cells) are perilously perched above the waves on a narrow shelf, accessed by several hundreds of steps.