In the years between Stonewall and the AIDS crisis, New York City was something of a hotbed of homosexual activity. Especially in the West Village and on the piers lining the Hudson. The piers especially were regularly used for sunbathing, cruising and more. So what did that look like? On a sunny day, something like this:
Of course not everyone was into getting it on outside, and for them options included going underneath the then-elevated West Side Highway or heading to the nearby Pier 48, "a rotting wooden structure where sex could be had anytime of the day or the night." That one looked like this. Want a better sense of what those piers were like at night? Might as well start with Edmund White (check out the first few pages of this one).
Times have very much changed since the 1970s, but a portion of the gay population still flock to the West Side piers (specifically the Christopher Street pier), however now instead of sexual liberation they have bitter neighbors. [h/t Kenneth in the 212]