Kim Kardashian Soaps Herself Up in Pool While Camping, on Video

Kim Kardashian found the oasis in the desert ... scrubbing herself down in a cold bath to get clean while camping, in a moment her sister likened to the beginning of a pornographic movie!

On the newest episode of "The Kardashians" -- released Thursday -- Kim, Kris Jenner and Khloé Kardashian took a luxury RV out to Joshua Tree, California for an evening of glamping ... a choice city girl Kim said had her feeling nasty.

After just one day at the campsite, Kim claimed she'd "never felt dirtier" and needed to shower ... 'cause she simply refused to go to bed dusty.

KK and her fam then went out to a large tub -- the size of an above-ground swimming pool -- and she hopped in wearing a set of matching Skims shapewear.

Kim whipped out a loofah -- something she says she always carries -- and some soap to rub herself down. Watch the clip ... she really goes to town on her bod, pouring soap over every inch of her body.

The scene prompted Khloé to say it looked like the "setup of a porn" ... totally inappropriate for anyone to watch. Khloé also adds she was worried about getting murdered out in the desert -- so, she was on high alert the entire time.

Khloé also mocks her sister's showering in the episode ... exaggerating the way Kim soaped herself up with a series of body rolls and other sexualized motions.