Oldest National Park east of the Mississippi, Acadia National Park is located in downeast Maine. It is the only national park in the state of Maine, and it occupies most of Mount Desert Island (locals pronounce that like "dessert") and a portion of neighboring Isle au Haut (pronounced "eye-la-ho"). The town associated with it would be Bar Harbor, Maine, though the town is quite separate from the park itself.
Human inhabitation in the area goes back at least 6000 years, to the Penobscot and Abenaki native American tribes. The area was actually discovered by the French a few decades before the pilgrims came to Plymouth. They named it "Isles des Monts Desert", and the name's English equivalent remains today. Control of the area passed to the English in 1759, with the conclusion of the French and Indian War.
Areas of Maine above Portland were generally very sparsely populated during the late 1700s and early 1800s. However, towards the end of the 19th century, Mount Desert Island became a posh retreat for the new strata of extremely affluent American profiteers. Acadia was the summer retreat of such names as Rockefeller, Morgan, Carnegie, Ford, and Vanderbilt.
An early environmentalist named George B. Dorr, the "father" of Acadia National Park, began to agitate for some sort of control on the rapidly increasing development in the Bar Harbor area. He founded, in 1901, the Hancock County Trustees of Public Reservations. This foundation managed to purchase over 6000 acres of land on Mount Desert Island. After several years of petitioning the federal government, the area was recognized as "Sieur des Monts National Monument" in 1916, and granted full national park status as "Lafayette National Park" in 1919. The name was changed to "Acadia National Park" in 1929.
Today, Acadia includes over 46,000 acres, 30,000 of which are on Mount Desert Island. Visitors to the park are presented with numerous options, such as the Carriage roads that criss-cross around Mount Desert. Cadillac Mountain, on Mount Desert, is 460 meters above sea level (about 0.28 miles). There is an ongoing friendly dispute between residents of the Bar Harbor area and those of Eastport, Maine (the easternmost town in the nation) as to who actually gets to see the sunrise first, thus claiming the title of "First in the Nation to Greet the Sun". Technically speaking, the summit of Cadillac can claim this between October 7 and March 6. Also of interest is Thunder Canyon, a rocky inlet of the Atlantic Ocean that produces huge amounts of spray, so named for the equally loud sound produced by waves breaking on the rocks.
Flora and fauna are diverse. The most common feature, of course, is the usual assortment of coastal Maine trees: pine, burch, and spruce. Bald eagles and peregrine falcons are also often seen in the park. Many marine mammals that are usually absent in developed sea fronts pay visits to Acadia, such as the orca (killer) whale and white-sided dolphin.
Finding Acadia is pretty easy. Take I-95 north from pretty much anywhere until you see a big "Welcome to Maine" sign. Continue north to Augusta, and then take route 3 east towards Belfast and Castine. You'll see signs for Bar Harbor and the park along the way, for sure. It's pretty hard to miss.
Sources: Personal knowledge, having lived in Maine all my life, and http://www.nps.gov/acad/
Submitted in conjunction with the U.S. National Parks and Monuments Everything quest.