This dataset contains carbonate system data collected by scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center to investigate the effects of carbon cycling, coastal and ocean acidification on the Tampa Bay estuary located in west central Florida, USA. These data were collected using an autonomous instrument called the Ocean Carbon System (OCS) deployed on the seafloor in Tampa Bay. The OCS consists of five sensors integrated into a Sea-Bird Scientific (Satlantic) STOR-X submersible data logger including a Seabird 16plus CTD, a Satlantic SeaFET pH sensor, a Pro-Oceanus CO2-Pro CO2 sensor, an Aanderaa oxygen optode, and a Wetlabs Eco-PAR sensor. The dataset is a time series of carbonate system parameters including: water temperature (Celsius, °C), conductivity (siemens, S), pressure (decibar, dbar), salinity, pHT (pH on the total scale), carbon dioxide (ppm), pressure from the CO2-Pro Infrared Gas Analyzer (IRGA) (millibars), dissolved oxygen (micromoles) and photosynthetically available radiation (microEinsteins). Each parameter was measured every hour for 24-hour time periods during extended deployments ranging from weeks to months.