Estuaries, where freshwater and saltwater interface, form some of the richest ecosystems on earth, capable of producing five times more plant material than a cornfield of comparable size while supporting great numbers of fish, birds, and other wildlife.

The South Slough of Coos Bay is the largest such web of life on the Oregon coast. The South Slough Estuarine Reserve Interpretive Center (Seven Devils Rd., 541/888-5558, www.oregon.gov/DSL/SSNERR, 10 a.m.–4:30 p.m. daily Memorial Day–Labor Day, 10 a.m.–4:30 p.m. Tues.–Sat. Labor Day–Memorial Day, free), four miles south of Charleston, will help you coordinate a canoe trip through the estuary and offers guided hikes as well.

The center looks out over several estuarine arms of Coos Bay, the largest harbor between San Francisco Bay and Puget Sound. These vital wetlands nurture a variety of life forms, detailed by the placards captioning the center’s exhibits. The coastal ecosystem is presented by the “10-minute trail” behind the interpretive center. The various conifers and the understory are clearly labeled along the gently sloping half-mile loop.

Branch trails lead down toward the water for an up-close view of the estuary. Down by the slough, you may see elk grazing in marshy meadows and bald eagles circling above, while Homo sapiens harvest oysters and shrimp in these waters.

Beginning near the visitors center is the easy three-mile estuary study trail, which follows Hidden Creek from the wooded uplands down the valley to a boardwalk that winds through fresh- and saltwater marshes and leads to several wildlife observation points.