Of course, there is more to a wetland than muck and vegetation. Most of them are transition zones between upland areas and larger waterways like rivers, lakes or the ocean. A transition zone might include a flood plain, riparian area, delta or estuary. Some wetlands are found in low-lying areas of woods or fields. An area's geology sometimes creates a wetland because water seeps to the surface, as it does in a small spring.
Wetlands can even be temporary, like a vernal pond.
These ponds fill with rainwater each spring or fall, but may become dry over the summer. We often think of wetlands only as swamps. You would be amazed at how many different kinds of wetlands there really are. And each type has unique features. Because there are so many, scientists categorize them in several groups and types.