Island of the Blue Dolphins is a 1960 children's novel written by Scott O'Dell and tells the story of a 12-year-old girl stranded alone for years on an island off the California coast. It is based on the true story of a Nicoleno Native American left alone for 18 years on San Nicolas Island during the 19th century.

How long did karana live on the island alone? Okie... think carefully first, then make a decision:
To answer the question, consider the following: It is based on the true story of a Nicoleno Native American left alone for 18 years on San Nicolas Island during the 19th century. So, the answer is 18 years.