I saw the movie first, with Nicole Kidman, Sam Neill and Billy Zane, and realized I had the book, so read it. Really good book, brought this landlubber reader right down to water level in the middle of the Pacific Ocean. Memorable, well-drawn characters. Action cuts from one yacht, with a madman and the new bride, to the other yacht, which is slowly sinking, with the husband and two other people aboard. The husband and wife are frantically trying to reunite in the vast, empty sea. Tension abounds on both boats. The boats go further apart, then come closer, trying to find each other as the hours pass, the water rises in the sinking boat, and darkness falls. Climax? Wow!
I wasn't surprised to find the book was out of print, but it shouldn't be, it's that good. A classic. Written in 1963. Williams born when Joseph Conrad was alive. I bought it and many other Perennial Library paperback mysteries 15 years ago for $.99 each, and was amazed to find it made into a current movie with big stars.