I would not recommend walking on those lovely tussocks of grass, as we suspected water underneath..
This particular marsh is an estuary, a lively place where fresh and salt water meet. Areas like this are probably where the first tetrapods emerged from the sea, leading to the variety of land-dwelling vertebrates we have today. Estuaries are rich ecosystems, providing places for fish to spawn, insects to lay eggs, and migrating birds to rest and feed. Without marshes, the fish populations on which so many human cultures have depended for food would undergo an even sharper decline than they have.
The largest grass clumps here are spartina, a plant that has evolved to expel salt from its tissues. Most grass would die quickly under these conditions, but not spartina. The roots of this tough plant hold onto whatever soil they can grab and form part of the matrix of the shoreline. Without plants like marshgrass and mangrove, the flow of all that water might well eventually turn Ohio into oceanfront property.
For all their toughness, however, marshes are globally threatened--often by development. Some of this development results from our human desire to control water, particularly the desire to pave over places where water wants to be. Often, though, the threat comes from being loved to death. People tend to like having views like these off their decks and porches. (I certainly would, and we did indeed spend a couple of nights on this island.)
However, just a few miles away, on the edge of a preserve, this is the view:
Hatteras Island is considered relatively undeveloped, but I doubt that any fish are spawning or herons hunting in neighborhoods like the one in the distance.