New Yorkers used to joke that dead bodies and hypodermic needles would be found in the body of water between Manhattan and New Jersey. New York drinking water, on the other hand, use reservoirs and has always been excellent. Many people drink unfiltered tap water.
Recent effort regarding pollution has helped the Hudson. Now people walk close to the river without a thought. There is also free kayaking (yes, can you imagine anything free in this city?) between May and October.
Three piers, at 72nd Street, 56th Street and Houston Street, have kayaking available to the public. The lines in front of the piers are sometimes long in the summertime.
Related posts: Here's to the Human Condition, The Sky is Falling and The Majestic Ansonia.