Hmm...does going into a mudpit that's at a beach count?
I'm usually not terribly crazy about public WAM but this one is just too convenient. It is on my way home from work. The mudpit feels like a cross between sand and clay, and it is about three feet deep in the middle (very nice mud).
I can't say I find it erotic since I tend to be at my best in a private location. But in the summer, it is relaxing after a long day at work to go sit in the mud for a bit and then rinse off at the lake.
Sometimes it's amusing when somebody is obviously meeting this mudpit for the first time. The best line I ever overheard there was from an attractive young woman in a bikini standing in the middle of the mudpit. She was obviously comfortable and familiar with it, and she was addressing a very reluctant young man who just didn't know what he thought of...THAT.
"You are human. You have an immune system. Now GET INTO THE MUD!"
Nessie