A "sister park" agreement between Grand Teton National Park and an Argentine national park is building more than good will -- it's leading to more durable hiking trails in the Austral Andes.

Trekking to Canyon de Chelly National Monument in winter offers a number of pluses -- a respite from high summer temperatures, no crowds, and lodging rates well below summer's high-season pricing.

While the main attraction is underground at Mammoth Cave National Park, there's quite a bit of history to appreciate above ground. Long before the park was established, homesteads dotted the heavily forested rolling hills. The land that was acquired for the national park displaced small communities that left their mark in the more than 80 cemeteries, churches, and homesteads that can be found within the park's borders.

A Nevada man paid $2,500 for mussels at Glen Canyon National Recreation Area, but they weren't served up at some ritzy restaurant. No, the boater was fined $2,500 for failing to have his craft inspected for quagga and zebra mussels before launching on Lake Powell.