Called the Pa-Hay-Okee or River of Grass by the local Seminole tribe. It's 97km/60mi wide and flows so slowly that I couldn't see the water moving, draining Florida's main lake into the state's southern coast. Ecologically it's fascinating, with like 4m/12ft of elevation gain across it representing multiple ecosystems linked to how much water persists throughout the year. In the Rockies the ecosystems change every 300m/1000ft, here it's whether the water is at your ankle or your knee.

Highly recommended. It's remarkable.