All this water action in both directions—freshwater coming from inland, saltwater encroaching from the Atlantic—results in the phenomenon of the salt marsh, the single most recognizable and iconic geographic feature of the South Carolina coast, also known simply as “wetlands.” (Freshwater marshes are more rare, Florida’s Everglades being perhaps the premier example.)

Far more than just a transitional zone between land and water, marsh is also nature’s nursery. Plant and animal life in marshes tends to be not only diverse, but encompasses multitudes. Though you may not see its denizens easily, on close inspection you’ll find the marsh absolutely teeming with creatures. Visually, the main identifying feature of a salt marsh is its distinctive, reed-like marsh grasses, adapted to survive in brackish water. Like estuaries, marshes and all life in them are heavily influenced by the tides, which bring in nutrients.

The marsh has also played a key role in human history as well, for it was here where the massive rice and indigo plantations grew their signature crops, aided by the natural ebb and flow of the tides. While most marsh you see will look quite undisturbed, very little of it could be called pristine.

In the heyday of the rice plantations, much of the entire coastal salt marsh was crisscrossed by the canal-and-dike system of the rice paddies. You can still see evidence almost everywhere in the area if you look hard enough (the best time to look is right after takeoff or before landing in an airplane, since many approaches to regional airports take you over wetlands). Anytime you see a low, straight ridge running through a marsh, that’s likely the eroded, overgrown remnant of an old rice paddy dike. Kayakers occasionally find old wooden water gates, or “trunks,” on their paddles.

In the Lowcountry, you’ll often hear the term pluff mud. This refers to the area’s distinctive variety of soft, dark mud in the salt marsh, which often has an equally distinctive odor that locals love, but some visitors have a hard time getting used to. Extraordinarily rich in nutrients, pluff mud helped make rice a successful crop in the marshes of the Lowcountry.

In addition to their huge role as wildlife incubators and sanctuaries, wetlands are also one of the most important natural protectors of the health of the coastal region. They serve as natural filters, cleansing runoff from the land of toxins and pollutants before it hits the ocean. They also help humans by serving as natural hurricane barriers, their porous nature helping to ease the brunt of the damaging storm surge.