When one takes a dump in a large body of water such as a pool or lake while actually in the body of water. this has sub categories of floater and sinker. floaters obviously float, which is a hard task to produce the appropriate density and buoyancy necessary to float.
This is not to be confused with a depth charge which is where one drops feces into a large body of water from outside it such as off a dock or pier.
"I just took a major aqua dump and it was a floater. it had to be the corn I ate earlier."
"Dude, don't depth charge it, if you gotta go, aqua dump it."