Sundiver is a bit of a challenging read at times. There are many times where it left me wondering about the life of Jacob Demwa before the story, as it constantly gets into his past. The story is as much mystery as science fiction.

Demwa is working with intelligent dolphins after an exciting life. He's quite content, but is talked into joining an expedition to Mercury to meet with the crew doing the Sundiver experiment. They've found what they believe to be life on the Sun.

The politcal situation is tough. This is a time where Earth is in contact with many alien species, and not all are comfortable with Earth's position. There is status associated with bringing other species up to sentience, and humans have done so with two - dolphins and chimpanzees. Worse in some aliens' eyes, humans don't treat the species they have helped as servants.

The plot is extremely convoluted, and I really don't think this is Brin's best work. It's very hard to keep up with whodunnit. Demwa's past keeps intruding, which would not be so bad if there were novels we could read about it, because it's quite clear that he did some amazing things.

All this does not make Sundiver a bad story, just a particularly complicated one. On the whole I enjoyed it, but there were many details I could have done without... or would have enjoyed more if there were a novel I could read about when those events happened.