Info taken from the DownEast Scenic Rail website:

From canopied forest where the light sparkles through the tree tops as chickadees and nuthatches bounce from limb to limb, to open marshland where beaver, heron, turtles, and moose might be seen, the restored section of the Calais Branch Lines gives passengers a view not seen since the wealthy “rusticators” traveled from the cities to their summer homes on the Line.
You’ll travel over bridges, roll past schools and houses, hear the clack of the rails muffle on the thick woodland moss, and delight in the sound of the horn at the crossing. Watch as the powerful engine moves from the front to the back of the train to take you to Washington Junction rail yard where you’ll see the heavy equipment that keeps the rail running, and pass train components and cars currently being restored for use on the Downeast Scenic Railroad before coming back to the Ellsworth depot. On the way be sure to look for the nests of the giant osprey, and the big beaver hutches in the wetlands! In addition to exceptional views of wetland marshes, glacial erratica including massive boulders, river and stream crossings, while traveling and working on this stretch of the line we have observed many forms of wildlife including osprey, blue herons, bald eagles, moose, deer, snapping turtles, beavers…and bears!
The current traveling time is roughly 90 minutes, and traverses a 13-mile section of the restored railroad. Water and light snacks are available for purchase, and you are welcome to bring your own picnic lunch.*

At the core of the Downeast Scenic Railroad Project is the rehabilitation of the Washington Junction/Ellsworth to Green Lake section of the Calais Branch Line to create a 24-mile round- trip excursion ride. Other project components include construction of storage/repair facility at Washington Junction.
You can explore the history of the Calais Branch Line here.