We took a cruise down the Potomac to Mount Vernon on the Potomac Spirit one day. Of course, we managed to pick the most humid day I think Washington, DC had seen up to that point this year. One hundred percent humidity. Not drip and dry. Just drip, drip, drip. Even so, it was a pleasant trip although I found myself disappointed by how polluted the Potomac appeared. There were several dead fish floating in the river. Still, we did enjoy Mount Vernon, even if time constraints didn't allow us to tour the inside of the mansion.