what state is treasure island in?
Sponsored Topics. Treasure Island is a city in Pinellas County, Florida, in the United States. As of the 2000 census, the city population was 7,450. According to the U.S. Census Bureau's 2004 estimates, the city had a population of 7,521. According to the United States Census Bureau, the city has a total area of 5.3 square miles (13.8 kmÂ²).