Okay, so two competing teams spend the whole book scheming to raise the Titanic--nothing as exciting as even a race--, and then in the last chapter an underwater avalanche covers it in mud and that is it. There is actually another chapter which winds the clock forwards a few geological eons and has aliens dig the Titanic out of a mountain, but what is the point of that?
The whole book consists of loose and disconnected threads that never come together. Even pointless ones, utterly lost causes; a girl--called Ada, after the computer language--life-long obsessed with the Mandelbrot set is developed (daughter of one of the people wanting to raise the old ship), and then summarily dismissed by a falling tree in a freak tornado.
Arthur Clarke may be a god among SF writers, but this is not a book worth reading. It has all the feel of a work that some old writer couldn't be bothered finishing properly, only wanting to get another one out of the door replete with some negative opinion (including a dig at wanna-be mathematicians!) and aimless futurology, mostly off the mark.
A very thin narrative, almost skeletally so, and equally sparse character developments not even benefiting from the crutches of very extreme circumstances.
It is a hopeless book, border-line interesting only because it was written in 1989 and spends its time speculating about the year 2012.