The four most common examples of wetlands are marshes, swamps, bogs, and fens. Marshes are found near streams, lakes, ponds, and rivers, and range from a few inches to a few feet deep. Swamps are home to water-tolerant trees or shrubs and contain saturated soils and standing water. Bogs are characterized by peat deposits, acidic waters, and a mossy floor, providing a habitat for numerous specially adapted organisms. Fens are similar to bogs, but are less acidic and have higher nutrient levels.