I was recently surprised by several unusually large, steep, and closely spaced wakes at Haines Point on the Potomac River at Washington, DC. It was after dark and I was sitting still and talking with another paddler about 50ft off the concrete retaining wall. Mr. Better Nightvision saw the waves before I did, sprinted, and met them head on, but I got caught flat footed. Waves reflecting off the smooth, convex wall interacted with the incoming waves and made for the wildest ride I've ever had on that normally staid portion of the Potomac. I was glad we were a group of more experienced paddlers that night, because it would have been capsize city for novices. Stuff that never happened before happens all the time.