Freshwater swamps are wetlands that contain woody vegetation. They are typically found on the edges of marshes, along river courses, and in wet depressions in forests, and are a common environment in southern Guam. The largest tract of swamp forest on the island is the Talofofo River Valley.

Usually the major species involved are Hibiscus tiliaceus and Barringtonia racemosa. Others that may be present are Pandanus tectorius, Cynometra ramiflora and Areca catechu.