The Voyage of Maeldun
12th century, Old Irish, Lebor na hUidre (Book of the Dun Cow). Royal Irish Academy, Dublin.
It was as though they were sailing through air. Beneath the boat they could see another land.
Maeldun has been blown by a storm into an enchanted sea. Among islands of giants, mysterious ladies, apples, strange buildings and strange creatures, he comes to an island where the sea, like a meniscus, towers over the shore below. Maeldun and his crew look down and see terrified people on the beach throwing nut shells at them.
Another island is like a smooth tower rising out of the sea, with only a single door into it, which is locked.
They come to a part of the ocean where the sea is like glass, green glass. Maeldun and his crew can see clearly down to the gravel and sand of the seafloor as their boat moves over it. Then they come to an area of the sea where the water is like a mist and it feels as though they are sailing through the air and that their boat will not be supported by it. Beneath the boat they can see another land; a knight fights with a dragon that perches in a tree and plucks cattle to eat from a field nearby. Anxious about the buoyancy of their craft in the mist through which they are floating, they sail nervously on.