If you're interested in the Celtic saints, today's the feast of one of the most important - Brendan the Navigator. More well known in medieval Europe than St Patrick, this 6th Century Irish monastic was intelligent enough to discover America nearly a milennium before Columbus and leave well enough alone.
Amongst the adventures recounted in his Navigatio is the incident when St Brendan and his companions made camp on a small island, celebrated Mass and lit a fire to prepare some food. To their surprise the island began to move - they rushed back to their boat and were amazed to discover that what they thought was an island was in fact the whale Jasconius. (Another depiction can be found in this 15th Century German manuscript.)