The Delaware River Basin has a very diverse ecosystem with a wide variety of wildlife. Eagles, bears, snakes, insects, beavers, otters, herons, Canadian geese, fish, eels, deer, and other animals can be found along the river banks.

The Delaware River is a massive, undammed ecosystem home to a surprising variety of wildlife. In the water, you'll find over 100 species of fish, including the American Shad, Atlantic Sturgeon (which can grow up to 14 feet long), and the catadromous American Eel. The river is also a critical habitat for freshwater mussels, which act as natural filters for the water. Along the banks and in the sky, Bald Eagles are a common sight, having made a massive comeback in the region. You might also spot North American River Otters, Beavers, and Mink playing near the shoreline. In the more rural upper sections of the river, it is not uncommon to see Black Bears or White-tailed Deer crossing the water. During the spring, the Delaware Bay at the river's mouth hosts the world's largest population of spawning Horseshoe Crabs, a prehistoric species that has remained virtually unchanged for millions of years. This diversity makes the river a premier spot for birdwatchers and nature photographers in the Mid-Atlantic.