Last Saturday I went on a solo 25 km (15.6 mile) walk on the towpath that goes along the C&O Canal & the Potomac River. Instead of going on a continuous course, I did 2 out-and-back hikes, returning to my starting spot in between. That way, I didn't have to carry my lunch and carried less water than I would have otherwise.
I started at 9:35 from Lock 21, also known as Swains Lock.
Walking due west, I arrived at Lock 23 (Violette's Lock) at 11:20. My total walking time, excluding brief stops to take pictures, was 102 min. The distance between Locks 21 and 23 was about 5.3 miles. My average speed was, therefore, about 3 miles/h (4.8 km/h).
I arrived back at Lock 21 at 13:15, taking once again almost exactly 102 minutes. After a 30-min lunch break, I started walking due South and arrived at Lock 18 at 14:34. The distance between Locks 21 and 18 was about 2.5 miles. And my average speed, despite the fact that my legs were now tired and sore, was still about 3 miles/h.
Another view of Lock 23
After a very brief rest, I started my return trip and I arrived back at Lock 21 at 15:30. Again, my average speed remained the same at 3 miles/h. The temperature during the day had been predicted to go up to about 31 °C (88 °F) and it was humid, but I felt comfortable throughout the walk. Afterwards, the soreness in my legs quickly went away.
There is an annual series of 50 km, 80 km, 100 km hikes along the C&O Canal from Washington, DC to Harpers Ferry, West Virginia. I may attempt one of them next spring.