went to the gems of beaches at Breezy Tip and Fort Tilden yesterday. they are only really accessible if you have a car and/or bike.
they are actually pretty much scaled down versions of sand dune-d cape cod beaches only actually still in the NYC metro area (right off brooklyn/queens) about 30min drive from williamsburg.
there's tons of sand dunes that have paths that lead to.... nowhere... watch out of couples having sex (mostly gay dudes though).
the beaches were shockingly pristine and clean... and empty.... this was on a 84ºF Saturday afternoon (yesterday). These beaches are actually nude friendly. I was happy to notice some very attractive topless females (rare for "nude friendly" places). At one point my wife and I were in the middle of nowhere and said "well its all gay guys here..." she proceeded to take off her bikini top and dive into the water.
its very very bike friendly. even the main roads have dedicated bike lanes. there's all these paths that transverse through the sand dunes right from the parking lot.
the area was formerly a military base, and the parking lot was the take off/landing strips its just this massive flat land (perfect for checking your 0-60mph car times).
I was afraid to visit throughout the summer because rumor has it... the beaches have been overrun by gays cruising for sex, and the dreaded hipsters...but even if party true... there's so much open space and free and super duper clean beach that its not really a bother... plus I actually saw some really attractive women topless and lounging/swimming/going about (the wife included).
its best to rent/bring a car and drive down and bring a bike/food/water. everything is only within 2-3miles you can just park at the Jacob Riis Park (its actually free) and then bike to the sand dunes (bring a bike lock there's actually bike racks provided at the dunes).