So the kids are at camp this week and I was able to ride my bike along the towpath up to Washington Crossing and back - I love that route! From Yardley it's about 10 miles round trip, so it is a perfect distance, and the scenery is gorgeous. Part of Delaware Canal State Park, the towpath is a great resource - I feel lucky we live so close to it. The 60-mile long Delaware Canal towpath runs from Bristol to Easton, where it connects with the Lehigh Canal and is a National Recreation Trail. Inspired by the success of New York State's Erie Canal, Pennsylvania began building a 1,200-mile system of canals to connect Philadelphia, Pittsburgh, and Lake Erie in the 1800s.  Teams of mules pulled cargo-laden boats (anthracite coal from the northeastern Pennsylvania coal regions was the primary product) along the canal path until the last paying boat went through the locks in 1931, when trains took over as
the preferred form of goods transport. 
Now it is ideal for biking, walking, jogging, fishing and one of my favorite activities - spotting wildlife. I have seen box and snapping turtles, ducks, geese, frogs, snakes, muskrats, herons and other interesting birds, and fish (the canal is stocked every spring). Lots of trees shade the path in the summer and provide beautiful foliage in the autumn. Passing under several quaint bridges (some are very low - ask my husband Joe about that sometime!), it is really pretty flat except a few fun hills. And it is well maintained by the Friends of the Delaware Canal, an independent, non-profit organization which works to restore, preserve, and improve the Delaware Canal and its surroundings. 
To learn more about Pennsylvania's canals, a visit to the National Canal Museum in Easton is extremely worthwhile. You can ride a mule-drawn boat, see canal artifacts and steer a miniature canal boat through its paces (there is also a small canal boat exhibit at the Crayola Factory in Easton - another fun trip!)