What is this hole underneath my bench seat for?

(2012 base regular cab 4cyl auto) Hi, new member and Tacoma owner here. I discovered this hole while vacuuming the carpet when noticed mud caked underneath the carpet. That hole goes right through the floor to the driveshaft and is kicking up water and mud through the hole into the carpet. Why is it there, and how do I seal it? Thank you in advance!

 

I think there should be a rubber plug there. At the very least, put some Gorilla tape or something sturdy over it. I'd even RTV a piece of something over it.

 

Definitely should be a grommet in it. I had to turn mine upside down due to it rubbing against the axle when I lowered my base model.

 

Grommet goes there as a plug

Someone may have popped it out to drain water

 

Welcome to TW…probably popped it out when they drug it out of the river..