This movie is quite surreal as I know it.
I remember distinctrly the protagonist being on a ship with a young sailor, for which he displays fatherly affection before him falling in the sea during a storm: the sailor returns later as a giant, or monster.
The protagonist then reaches an Island where he meets some sort of woman: maybe a succubus or mage.
It has many parts in common with greek mythology.
Thank you for your time.