The son of Aillil Edge-of-Battle, Maelduin was a Celtic hero who, along with his men, visited 33 mystical islands, of which I could only find 31. Maelduin was concieved when his father, Aillil, looted a church and raped a nun, who died giving birth. Maelduin was raised by his aunt, the queen of the land. His legendary journey began with the purpose of avenging the death of Maelduin's father.

The first two islands he encountered were where the murderers of his father had hidden, but he was blown off course as he neared the shores. He then encountered several more enchanting islands:

--giant ants
--beautiful birds
--a horse with dog legs and bird-like talons
--demons racing horses
--an empty castle filled with beds and food
--a forest filled with apples
--a monster that could move around inside its own skin
--fighting horses
--creatures composed of fire
--a palace whose only occupant was a cat, but was decorated with: "three rows on the wall of the house round about, from one door post to the other. A row there, first, of brooches of gold and of silver, with their pins in the wall, and a row of neck-torques of gold and of silver: like hoops of a vat was each of them. The third row (was) of great swords, with hilts of gold and of silver"
--a brass wall that split the island into sides filled with white sheep on one side and black sheep on the other
--a giant who guarded a boiling river
--the home of the Miller of the Otherworld
--weeping black-skinned folk
--walls of gold, copper, silver, and crystal
--a crystal bridge
--talking birds
--a hermit who watched over birds containing the souls of his children
--giant smiths
--a stream that flowed into the sky
--a silver pillar that held up a country called Anocos
--a queen who tried to seduce Maelduin and convince him to stay with her
--intoxicating fruit
--a bird that restored Maelduin's youth by telling him of a magic lake to bathe in
--a crowd of people constantly rejoicing
--a protective wall of fire
--an old man who got his meals from creatures of the sea
--cattle of all kinds, and an falcon that they followed elsewhere
--the same place where his father's killers had stayed. They begged him for mercy, and he made peace with them.

Alfred Tennyson made the hero popular with his epic poem "The Voyage of Maeldune," but the original name of the story was "Immram Curaig Maile Duin." It is a notable point that, while each of these islands represents a purity of one generally positive aspect of life, the travelers always moved on because at each stop they felt as if the realities they encountered were lacking something important.

The voyage (or immram) of Maelduin, like that of Bran the Blessed, and Saint Brendan, tells us much about what a Celtic Book of the Dead would be like. It also gives indications of why the Celts felt that the dead would be willing to leave the Otherworld (Tir na nÓg) and be reborn into the mortal world.