Tampa Bay, a large natural harbor and shallow estuary located on Florida's west-central coast, connects to the Gulf of Mexico. It comprises Hillsborough Bay, McKay Bay, Old Tampa Bay, Middle Tampa Bay, and Lower Tampa Bay. The Hillsborough River is the largest source of freshwater flowing into the bay, entering at downtown Tampa's Hillsborough Bay. Numerous smaller rivers and streams contribute to the bay's watershed, creating a diverse and expansive ecosystem.
In 1914, the challenges of traveling between Tampa and St. Petersburg led to the establishment of the world's first scheduled air service, the St. Petersburg-Tampa Airboat Line, which operated during the tourist season.
In 1917, the U.S. Army Corps of Engineers dredged a new shipping channel from the mouth of Tampa Bay to the Port of Tampa. This development transformed Tampa into a major shipping hub.
The opening of the Gandy Bridge over Old Tampa Bay in 1924 significantly reduced travel time between Tampa and St. Petersburg, shortening the distance to 19 miles (31 km). This improved connectivity facilitated economic growth in the Tampa Bay area.
Since 1946, the sea level in Tampa Bay has risen by 8 inches (200 mm), making the region highly vulnerable to the effects of climate change and rising sea levels. Its location, growing population, and the bay's geography further increase the risk from hurricanes.
In 1990, the United States Environmental Protection Agency recognized the ecological importance of Tampa Bay by designating it as an "estuary of national significance." Two National Wildlife Refuges, Pinellas and Egmont Key, are situated within the bay, and many of the islands and sandbars are protected due to their sensitive ecosystems and role as bird nesting sites.
In 2004, a major environmental incident occurred when 65 million gallons of acidic water leaked from a Cargill phosphate plant on Tampa Bay's southern shore. This spill severely damaged the surrounding wetlands.
By 2010, thanks to improved water treatment plants and stricter industrial discharge regulations implemented in the 1980s, Tampa Bay's ecological health significantly improved. Seagrass coverage, water clarity, and biodiversity reached levels not seen since the 1950s.
By 2010, the population of the Tampa Bay Area had grown to over 4 million residents. This growth stemmed from the development of communities around the bay, including Tampa, Clearwater, Bradenton, and St. Petersburg.
A significant ecological disaster occurred in April 2021 when a wastewater reservoir at the abandoned Piney Point phosphate plant failed. Over 200 million gallons of nutrient-rich mine tailings flowed into lower Tampa Bay, causing a massive red tide algal bloom that killed over 1,000 tons of fish and threatened seagrass beds.
In October 2024, Hurricane Milton caused polluted waste from the fertilizer industry, including byproducts from Mosaic's phosphate production, to flow into Tampa Bay. Both Hurricane Milton and Hurricane Helene disrupted phosphate fertilizer production in the area.