Danger Below!

This was an exciting adventure with a non-science mystery.
But it involve science/engineering issues.
It includes saturation diving and cryogenic scuba.
The latter was pretty cutting edge at the time and probably wasn't used for helium/oxygen
mixture as liquid helium is really cold.
I liked the references to other books, they were very appropriate given the mystery.
I looked up Peter Gimbel and it's possible that the movie about sharks that Rick mentions
is “Blue Water White Death”.