Start summer with a free visit to a national park. The National Park Service is waiving all entrance fees on June 21 – the first day of summer.

“The longest day of the year is the perfect time to take a short trip. Celebrate an extended Father’s Day with dad, the start of summer break with the kids, or a job well done with your favorite graduate,” said National Park Service Director Jonathan B. Jarvis, in a news release. “With 394 national parks across the country, you could opt to visit an old favorite or explore a new place. Find a reason to get outside and enjoy the extra sunshine at a national park near you.”

Every park has something for everyone; plan a visit at Soak in the day’s first rays on top of Cadillac Mountain in Acadia National Park , a traditional spot to watch the sun rise, or at the annual summer solstice program at Casa Rinconada in Chaco Culture National Historical Park in New Mexico.

Take a free bus tour of Zion National Park in Utah or Tallgrass Prairie National Preserve in Kansas or a scenic wagon ride at Oxen Cove Farm in Maryland; get a free Cajun dance or music lesson at Jean Lafitte National Park & Preserve in Louisiana; watch a sled dog demonstration at Denali National Park and Preserve Alaska; visit with White House in Washington, D.C. artist Peter Waddell; or tour the Three Sisters Lighthouses in Cape Cod National Seashore in Massachusetts.

Commemorate the 150th anniversary of the Civil War with a Camp for Kids at Cedar Creek & Belle Grove National Historical Park in Virginia; a guided caravan tour of Stones River National Battlefield in Tennessee; or a living history event at Vicksburg National Military Park in Mississippi.

As the longest day of the year draws to a close, watch the sunset at a beach party at John Muir National Historic Site in California or during a guided stroll at Chattahoochee River National Recreation Area in Georgia, Padre Island National Seashore in Texas, Frederick Law Olmstead National Historic Site in Massachusetts, or White Sands National Monument in New Mexico.

The action continues into the night with a Star Party at Grand Canyon National Park in Arizona and a Night Sky program at Chaco Culture National Historical Park in New Mexico.

Additional fee free days in 2011 are National Public Lands Day on Saturday, Sept. 24 and Veterans Day weekend, Nov. 11-13.