Yes, the Rainbow River in Marion County, Florida, is a pure freshwater system. It is fed by Rainbow Springs, which is one of the largest and most productive artesian spring systems in the world, pumping approximately 410 million gallons of fresh, crystal-clear water every single day. Because the water comes from the Floridan Aquifer, it maintains a constant temperature of roughly 22°C (72°F) year-round and is incredibly transparent, allowing for visibility up to 200 feet deep. The river is designated as an "Outstanding Florida Water" and a National Natural Landmark, serving as a vital habitat for native freshwater flora and fauna, including manatees, turtles, and various species of fish. Unlike coastal "brackish" rivers that mix with the ocean, the Rainbow River remains entirely fresh throughout its 5.7-mile run until it merges with the Withlacoochee River, making it a premier destination for tubing, snorkeling, and kayaking in a pristine inland environment.