Treasure Island is a city in Pinellas County, Florida, United States. It is situated on a barrier island in the Gulf of Mexico. As of the 2020 census, the city population was 6,584. The area of Treasure Island was originally settled in small communities by the Tocobaga around 300 AD. The Timucua traded with other Native American tribes in the area until the arrival of Pánfilo de Narváez in 1528. De Narváez decimated the indigenous people before leaving the area in search of gold.