The Withlacoochee River ultimately discharges into the Gulf of Mexico on the border of Citrus and Levy counties. Rainbow Springs has the fourth largest flow of all Florida's springs and provides fresh water to the Rainbow and Withlacoochee rivers.

Rainbow River in Marion County, Florida, is a purely freshwater river. It is a "first-magnitude" spring-fed system, meaning it is fed by the Rainbow Springs group, which discharges over 400 million gallons of crystal-clear freshwater every single day. The water remains a constant 72°F (22°C) year-round, making it a popular destination for tubing, kayaking, and snorkeling in 2026. Because it is freshwater, you will find a different ecosystem than Florida's coastal rivers; the river is home to freshwater turtles, various species of bass and sunfish, and lush underwater "grasses" that stay vibrant due to the intense clarity of the spring water. The river flows south for approximately 5.7 miles before merging with the Withlacoochee River. Because there is no tidal influence or salt intrusion, the water is exceptionally "soft" and clear, often allowing for visibility of up to 200 feet horizontally. This freshwater environment is protected as an "Outstanding Florida Water" and an "Aquatic Preserve," ensuring that its pristine, non-saline character is preserved for future generations of outdoor enthusiasts.