I live right outside Philadelphia, I remember when that happened. It was a big deal at the time and lots of blame flying around with the Duck Boat company
The currents in that part of the river are notoriously bad right near the Ben Franklin Bridge and a lot of drownings happen as a result
As an aside, that area of the river has the USS New Jersey on the Jersey side and the USS Olympia on the PA side. Huge tourist area. Less than a few miles down river is the Philadelphia Navy Yard