Biscayne National Park in Florida is just the latest unit in the National Park System to propose an increase in camping fees to help pay for maintenance and other needs not being met by Congress.

Take a trip to the Delaware and Leigh Navigation National Heritage Corridor in eastern Pennsylvania and you'll find a bucolic landscape with quaint towns and rich history that delves into the nation's industrial past.

Since 1986, national park visitors across the country have turned to the Passport To Your National Parks program to preserve cherished memories of their park travels by collecting ink cancellations at every national park they visit. This year the program is celebrating its 35th birthday. For 35 years, the Passport to Your National Parks program has assisted visitors explore and protect the vast natural, cultural, and historic treasures of America.

The world's longest cave, protected as Mammoth Cave National Park in Kentucky, is longer than you might have thought. Recent efforts by the Cave Research Foundation have mapped eight more miles for the cave, bringing its currently accepted length to 420 miles.