What is the name of this movie?

don't know where to look, but does anyone remember a 1960's or early 1970's Space/Future of a meteor that was headed towards an underwater city in the Atlantic and there was a submarine stealing gold, and a man that swam like a dolphin, etc, and the City was evacuating due to a possible impact. I thought it was Call Atlantis City or something, perhaps you could check around for me, I watched this as a kid, and wanted to find it again. Thanks.