This course provides a structured introduction to the fluid mechanics related to natural fluid systems, including streams, rivers, lakes, the atmosphere, and oceans. The course is structured around the basic flow processes and features common to many environmental flows, including boundary layers, free surfaces, gravity and reduced gravity, diffusion and dispersion, the effect of the Earth’s rotation (NOT seen in your toilet bowl, you will learn!), turbulence, density stratification, sediment transport, unsteadiness, and viscosity. We learn these concepts through the lenses of many relevant environmental flows, including the atmospheric boundary layer, hurricanes, streams and rivers, lakes, and more. Some laboratory demonstrations are also typically conducted as part of the class and class projects allow students to go into depth about a topic of their choice.