"Extreme" to me these days is still fisting and huge dildo play (that's pretty damned extreme, in my book--fucking OUCH!), "gape" (sorry, folks, that is just something I do NOT need to see, nor do you need to show), sounding (EWWWWW!), violence/heavy BDSM, scat, bestiality, CP, etc.

Watersports is pretty tame to me, but that's pretty much as kinky as I get in my own sex life, so I kind of consider anything beyond what I'm comfortable doing to be "extreme." Anything beyond what is considered to be the standard norm, I guess, though obviously leather sex has come a long way in the world.