Tampa Bay is a large natural harbor and estuary along the Gulf of Mexico on the west central coast of Florida, comprising Old Tampa Bay, Hillsborough Bay, McKay Bay, and New Tampa Bay.

The bay has been a brackish estuary with a wide mouth connecting it to the Gulf of Mexico for approximately 6,000 years. Prior to that time, it was a large fresh water lake, possibly fed by the Floridan Aquifer through natural springs. Though the exact process of the lake-to-bay transformation is not completely understood, the leading theory is that rising seas levels following the last ice age coupled with the formation of a massive sink hole near the current mouth of the bay created a connection between the lake and the gulf.

Humans have lived near the shores of Tampa Bay for millennia, possibly as long as 12,000 to 14,000 years. The first local people to fully adapt to a sea-side lifestyle was the Manasota culture, beginning around 5,000 - 6,000 years ago and eventually evolving into the Weeden Island culture . Approximately 1,100 years ago, the Tocobaga developed near present-day Safety Harbor along Old Tampa Bay. These were the people living in the area at the time of first contact with Europeans.