The “Scrubbing Sirena Beach” mission in Super Mario Sunshine isn't exactly the most exciting objective in the game. Mario is tasked with cleaning up 95% of the beach before he can earn a Shine. Normally the task is a bit time-consuming, but a bug introduced through the Super Mario 3D All-Stars version of the game makes the mission a snap.
As you can see in the video above, the player looking to tackle the “Scrubbing Sirena Beach” mission doesn't get anywhere near the clean-up goal, yet he's awarded a win. What's causing this bug to pop up? Players aren't sure just yet, and dataminers are trying to figure it out. Being able to activate the glitch at will would be great for speedrunners, but as of right now, it seems players are happening upon the bug randomly.
If/when the reasoning for this bug is discovered, you can bet that speedrunners will push it to the limits!