Big Bend National Park and the Rio Grande Wild and Scenic River claim 245 miles of this renowned river. And while many of those miles wend their way through rugged and remote canyon country, sections of the river nevertheless are on the state of Texas’ list of impaired water bodies. The primary concern is high total dissolved solids (high salinity), but bacteria can be a problem in the very upper reach.

Riptides along Cape Hatteras National Seashore are some of the most dangerous along the East Coast, but budget woes have left the question of whether there will be lifeguards on the seashore this summer up in the air.

A swarm of earthquakes, with one registering a 4.8 magnitude, shuddered parts of Yellowstone National Park on Sunday, with smaller quakes before and after that one reported by seismologists.

You wouldn't immediately think caves would be a sink for garbage, but quite a bit of junk collects in Lehman Cave at Great Basin National Park each year. Recently, volunteers hauled more than two tons of garbage out of the cave.