I'm hoping someone out there has a better memory than I do, as I'm trying to find this comic. It was a DC comic (I'm fairly certain it was DC, but it might have been Gold Key/Dell) from the late 1960s. As a kid I thought it was an SF/mystery title, but now I think it might have been some sort of "strange/mysterious romance" type. It was missing its cover, so I do not ever remember seeing the title.
The plot of the issue I recall concerned a sailor/deep sea diver who finds a beautiful and mysterious girl near the sea, and falls in love with her. She is apparently some sort of mutant/mermaid/hybrid, as she lives in the water and has trouble breathing on land. She could come out when it rained, and there was a scene of them kissing during a rainstorm.
Her home is on the sea bottom, in a wrecked ship (might have been submarine) that is perched near a deep chasm.
At the end he loses her when a storm causes her home to fall in the chasm.
I don't know why this comic has stayed with me after 40+ years. Maybe because I have been able to find all of my other childhood favorites, but this one has eluded me.
Thanks for any info anyone can pass along.