Sebastian is a city in Indian River County, Florida, United States. In 2010, the population recorded by the U.S. Census Bureau was 21,929. Sebastian is a principal city of the Sebastian−Vero Beach Metropolitan Statistical Area, which includes all of Indian River County. In 1715, several Spanish ships loaded with treasure (known as the 1715 Treasure Fleet) encountered a storm off the shores of the Treasure Coast and were lost. It is estimated that only a portion of the sunken treasure has been found. The value placed on the treasure lost from the 1715 fleet has been estimated at more than US$500 million. The per capita income for the city was $24,959 in 2010. VISIT OFFICIAL CITY SITE https://www.cityofsebastian.org