Really? I don't mean just off New Jersey, I mean you're in NYC and you jump in the water and there are Great Whites. I could find any articles on it, but I'd like to see one.
I wouldn't worry about sharks in NYC... The sludge has probably killed them all off! I'm sure jumping in the Hudson would cause you to melt rather quickly!
Diving in the Hudson River south of Albany and your wetsuits will soak up all of the hydrocarbon and PCB pollution. The river quality is bad on a good day and downright nasty after a good rainfall due to the wastewater treatment plants overflowing into the river. The quality gets worse the closer to NYC that you get. This type of diving "should" be left to a drysuit with a helmet/umbilical. No bottle is worth the kind of sickness you can get from rivers with extreme industrial and human waste. Their are plenty of state and federal websites that monitor river water quality. On another note have your friends be aware of the NY State "Archies" they like to keep historical stuff on the bottom and have strict recovery and reporting laws, SOOOOO keep it to yourself!
Does anyone remember the Seinfeld episode where Kramer starts swimming daily in the Hudson? Blade, Megalodons were as big as a house. How could that tooth be fake? As a kid, my family always went to OC NJ in the summer. The last time, I remember finding needles washing up on the beach along with other medical waste. Not sure where it was from. I do have very fond memories of Ocean City, though.