Key Out of Time by Andre Norton

Andre Alice Norton was a 20th century American science fiction writer. She also wrote historical fiction and contemporary fiction. Andre Norton was her pseudonym. She was the first woman to receive the Gandalf Grand Master Award from the World Science Fiction Society in 1977. Norton was awarded the coveted Damon Knight Memorial Grand Master Award from the SFWA in 1983. Key Out of Time is part of the Time Trader Series in which Ross Murdock and Arthur Ashe continue their adventure across space and time. Ross and Arthur are helped by Karara and two trained dolphins in Hawaika, which was settled by Hawaiian and Polynesian settlers. The planet Hawaikan is a warm tropical planet that is mostly ocean. It is so different from what they had expected that they decide to risk a time trip back in the planet's history. Just as they are about to use the time gate a storm blows up and Murdock is flung through the gate and into the planet's past. The time gate is destroyed and Murdock is left to cope with this different and alien world on his own.

This book is part of the "Time Traders/Ross Murdock" series.
Here are some other books from this series: