David Brin, 1983
Hugo Winner - 1984
Premise: Streaker is in trouble. The ship from Earth was only supposed to be doing some routine investigation of little-traveled star systems while the mostly-neofin crew gained in experience. They weren't supposed to find a lost fleet of unknown origin, then be chased by hostile galactic fleets who each want to be the sole recipient of whatever knowledge is there to be gained. Now the crew is hidden on an unknown planet, hoping to find a way to get through the massive space battle nearby and get home with their discoveries.
There are a lot of interesting concepts here. There is a huge, complicated, mostly hostile galactic society based on the idea of Uplift. Uplift is racism, slavery/indentured service and colonialism mixed with genetic engineering on an interstellar scale, as existing species modify 'younger' species into space-faring races in return for service. The existence of humanity challenges the idea of Uplift, as they apparently made it to the stars initially alone. Of course, humans are lifting up chimps and dolphins into fully sentient races in turn, which requires a complicated combination of responsibility and caution.
So: intelligent space dolphins. Most of the crew of Streaker are dolphins, including the captain. The dolphin culture is really interesting. I find it reasonable, given what I know of cetaceans, and beautifully conveyed through their own language and conventions.
The plot mostly follows the crew's efforts to repair their ship and find a way out of their situation, although there is danger from within the crew as well as without. It's complicated further by discoveries made on the supposedly-uninhabited planet they are hiding on. You also get snippets of the races fighting nearby for the right to capture and interrogate the Earth ship.
I found the book a bit slow on occasion, as there are so many characters and interlocking pieces of the plot. However, it was terrifically inventive throughout, and the pace meant that there was also an extended climax as each character's struggles came to a head.
4 Stars - A Very Good Book
List of Hugo Winners