'99 Honda Accord back floor of the driver's side is soaked.
 

I live in central floor and we just had a week of heavy rain which made the floor in the backseat driver's side completely drenched. There was an inch of water in the two dips on the floor and I couldn't find a way to prevent it. After a little research, I am assuming it is the sunroof drains causing it but I can't figure out how to locate which one it is. I am assuming it is the rear drains but I can't see them at all to figure out how to snake them or anything of the sort. Any suggestions?

There are drains for the sunroof on all four corners your car. The pic below shows two of the drains, although the other corners have them. The drains go down to each wheel well. You should be able to see the drains with the sunroof open. You may be able to pour some water on the trough with the sunroof open to see if it drains quickly.

http://www.hondapartsnow.com/diagram...f-1-456675.png