Maryland, Blackwater River

With millions of Americans packed around Chesapeake Bay, you’d think every inch had been explored. Think again. In Blackwater National Wildlife Refuge, soaring ocean levels are opening new water trails to some of the deepest reaches of habitat where protected species like bald eagles, peregrine falcons, and Delmarva fox squirrels thrive. Since 1938, a third of marshes in this 26,000-acre refuge have been submerged, offering paddlers better access to real wilderness.

If sea levels keep rising, you’ll soon be able to poke even farther into Blackwater. Glaciologist Mark Meier, Ph.D., of the University of Colorado, reports that glacial melt alone could contribute 7 1/2 inches or more to global sea level this century.

To ride the rising wave, head upstream from MD 335 on the Blackwater River for a 6-mile out and back through pine forest fronted by freshwater marsh. For a slightly longer paddle, try the nearby Little Blackwater River. On both courses, you’ll witness rich tide marshes ringed by encroaching development, an obstacle to the natural ebb and flow which allowed past ecosystems to adapt to change.

Contact: Blackwater National Wildlife Refuge, (410) 228-2677; http://www.friendsofblackwater.org/