This film (also being screened on July 5) is being shown as part of the BFI Southbank Dennis Hopper season. Full details here.
Chicago Reader review:
Dennis Hopper had his first starring role in this odd and arresting black-and-white mood piece about a young sailor who falls in love with a carnival worker who may be a mermaid. Made in 1960 but not released until 1963, it was the first feature of Curtis Harrington. A poetic, low-budget independent effort, it can't be called an unqualified success but certainly deserves to be seen. At moments it evokes some of the early magic of Jacques Demy, and as with Demy's first feature, Lola, it's questionable whether Harrington ever topped it in his subsequent, more commercial efforts.
Here (and above) is the trailer.