The Aquatic Mine is a treasure in Pikmin 2. The real-world object it is modeled on is a fishing bob. The treasure is found inside the game's only Toady Bloyster, located behind the Onions at the Perplexing Pool. The lake it is in can be drained, but that requires that an electric fence be demolished.
I've recently noted that changes in this planet's environment happen at a very rapid pace. Compared to how it was when I was here before, the Perplexing Pool has changed drastically. Due to frequent tectonic shifts, the region appears slightly different each time I enter it. It could be a natural phenomenon, but it's as if I feel the presence of a guiding hand. ...Maybe it's just my imagination running wild. - Olimar