Down the river, right after DC its the Naval Research Laboratory, in front of Alexandria. I worked there, and some crazy folks from Alexandria sometimes crossed the river in canoes to the NRL pier... That got terminated after 911, so they had to bike or drive all the way up around DC and down through Anacostia Air Force Base. Quite a much longer commute.
When an aunt worked there, in the 1950s, there was a boat from National Airport or thereabouts for NRL employees from Virginia. The boat wasn't very nice. It was an open boat, and in rainy weather, a sheet of plywood served to shelter the commuters. They were always glad when the boat was out of service and an Air Force boat replaced it.
