The Welsh name for Puffin Island is 'Ynys Seiriol' and refers to St Seiriol who established a monastery at the nearby headland at Penmon during the 6th Century. There are many stories about Seiriol walking to meet his good friend St Gybi who lived at Caergybi / Holyhead. The two friends often used to meet in the middle of Anglesey.
Seiriol would walk west in the morning, and then would return home walking East in the afternoon. With the sun on his back for most of his travels, his face would rarely catch the sun and he became known as the pale or white saint.
St Gybi walked east in the mornings and west in the afternoons and always had the sun on his face. St Gybi became known as the tanned or tawny saint.