These islands are characterized by river bottom forest types such as willows, American sycamore, shagbark hickory, green ash, and silver maple.

Crull's and Thompson's Island contain 156 acres (63 ha) of mature and old-growth forests.

The area is home to ospreys, soft-shelled turtles, great blue herons, kingfishers, common mergansers, mallards, and beavers.

The islands are home to the federally endangered clubshell mussel (Pleurobema clava) and the Northern riffleshell (Epioblasma torulosa rangiana).

The area was featured in "Brian Finch's Black Op," the November 3, 2015 episode of Limitless.