My wife had not intended to be topless.
We were at Happy Bay, just swimming and having a good time. The current was pretty strong. At one point she gets dragged under; and when she resurfaces her bikini top is rolled up over her tits. So she tries to pull it back down; but the strings are tangled and it doesn't work. So she run back to our towels, tits flopping out, as she realizes she's going to have to take the whole thing off to untangle it.
As she pulls it over her head and proceeds to untangle the strings, I remind her that Happy Bay is clothing-optional anyways; and that she doesn't even need it. And she's already topless. She takes a look around and sees there are other topless women. And she begrudgingly tosses her top to the side.
By the end of the day she's actually enjoying too.