One who immerses oneself in fecal materials with or without the use of a mask and snorkel
I was surfing the net when I came across a random pooba diver offering to pay people $100 to swim in their septic tank and film himself while doing it!
A Belarusian Diver is a sexual practice, mostly homosexual, when one partner is dressed in a latex suit (looks like a diving suit) and the second partner inserts his penis into a dressed one's mouth ("snorkel").
Another variant is when latex-clad partner lies on his back, another one inserts penis into his mouth and puts his testicles onto his eyes. This is "diving mask and snorkel".
"Dude, get your latex suit ready. We're playing Belarusian Diver today"