"Desert in the Ocean"

.. the acetic practices of the early Irish church could serve to purge the soul in this life in order to mitigate suffering in the next, and they also served to assist the souls of departed kindred and friends. Asceticism is etched in monastic sites such as Skellig, a bare rock in the sea dedicated to Michael the archangel, leader of souls into Paradise. The hardship of existence on a windswept height over the raging sea must surely have counted as penitential preparation for the perilous passage of the soul after death, and the pilgrimage to the top of the bare height can be seen as a Christian adaptation of Irish pagan practice of assemblies on heights in honour of their deities
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As well as living in "a desert in the ocean" like Skellig, undertaking the perilous sea-journey in search of such a retreat is also a feature of early Irish monastic asceticism. The eighth-century Navigatio of St Brendan thereby reflects contemporary monastic practice as well as pre-Christian tales of the journey of a mortal to an overseas Otherworld.

-- Maire Herbert, "The Celtic Otherworld and The Commedia"