The Media Luna Watershed contains various unique ecosystems, highlighted by the spectacular lake, Media Luna. This book was written to create attention to the fragile ecosystems within the watershed and the environmental impacts tourism and commerce is producing. Also, to provide the citizens within the watershed and tourists a field guide to the aquatic environment found throughout the watershed. This book covers the natural history to include aquatic vegetation, fishes, birds, amphibians, reptiles, and crustaceans that are commonly found within the watershed. This book begins with the history, both natural and social, of the creation of Media Luna as a park and ends with a discussion about environmental impacts that are currently occurring. In between, we introduce the reader to the natural history found in the watershed with nearly one hundred real photos for easy identification. With every image is a brief but precise description of the pictured species. The goal of this guide is to awaken curiosity and interest in the beautiful and diverse ecosystems found inside the Media Luna Watershed.