What is the theme in Swamp Thing by Alan Moore?

Another theme would be the natural world. As Swamp Thing is made of plant material and comes from the natural world, he has been used as an appropriate defender of ecological concerns, and the first few books in this volume are no exception.

The natural world is crucial to Swamp Thing for several reasons. Most apparently, he feeds upon the energy of the swamp. He must return to the swamp to reinvigorate himself from time to time. However, beyond that, Swamp Thing struggles for any reason to live in this volume, and he is eventually able to find peace in the swamp. Compared to the "red" world of humanity and its ills, the "green" world is serene, nonviolent, and beautiful.