Located on a tributary of Chesapeake Bay, the Smithsonian Environmental Research Center is the Smithsonian's outpost for research in the coastal zone. Its biologists study marine biology, terrestrial ecology, invasive species, global change, pollution and other critical environmental issues. Though SERC is headquartered in Edgewater, Md., its scientists do research on coasts around the world. Its 2,650-acre campus includes hiking trails that are open to the public Monday through Saturday, closed only Sundays and federal holidays.