Britney Spears Poses Nude During Vacation

Britney Spears is baring all on vacation ... stretching in the nude right up against some glass windows!

The Princess of Pop shed all her clothes and posed in the buff ... for a naked photo shoot inside what appears to be her vacation villa.

Britney shared the sultry snap on her Instagram -- she's anything but shy on social media -- and covered up her backside with a small rose emoji.

The only thing Britney's wearing are some tall dark boots ... and she's got her long, blonde hair down to her hips.

Britney seemingly snapped the nude pic after another fun day out on the water ... because the post before was a video mix of her on a nearly beached boat rocking a revealing dress and some other fun clips.

We saw Britney flaunting her assets in a bikini on a earlier this week, when she was jamming to a song by her ex, Justin Timberlake.

The newer boat video and the nude photo look to be from the same vacation.