The Silent Years -1927

On-screen nudity did not begin with Pre-Code cinema.  Just look at the offerings from 1927 silent movies and you find the wonderfully cute Clara Bow in Hula, It and Wings. 

She is caught topless for a couple of frames in Wings,



spends time bathing in Hula
(the stills are infinitely better than any screen grab from the surviving prints)



and she shows off her undies in It. 

Jacqueline Gadsden also looks sexy when wet in It, and you just have to love how the director and DP set up the scene so the camera stays on Ms. Gadsden's caboose as she gets out of the water.

Brigitte Helm also appears topless maybe, sort of, in the highly regarded Metropolis (1927).

But for real exposure you need to watch the short, Forbidden Daughters, in which Clarice Conwell hunts down her philandering husband and wins him back by getting all nekkid.

Along the way, she spends time observing the shenanigans in a harem, with Gladys Delores

and Kathyn Kay running around, suitably unclothed.