This is a strange film. It's essentially a comedy about a young bored suburban couple. They inherit money from an uncle and travel all around the globe, getting into various misadventures, including infidelities, for the both of them. Throughout it all they remain droll and unsentimental. It's actually a pretty charming film, although it's episodic and some episodes are much better than others. Some people think that it's Hitchcock's most autobiographical film, a portrait of Alma and him on their honeymoon.
The title comes from Shakespeare, some of the most brilliant lines he over wrote. Out of the mouth of Ariel in The Tempest:
Full fathom five thy father lies;
Of his bones are coral made;
Those are pearls that were his eyes;
Nothing of him that doth fade,
But doth suffer a sea-change
Into something rich and strange.