2003 Mustang GT convertible water leak

[Eightiesrock1980]

Whenever it rains, I get water under the rear seats in the back and on the floor a tiny bit if it rains hard enough on the driver side I plugged up all the holes on the floor on the driver side, but I’m still getting a little tiny bit on the floor, but most of the water is developing underneath the rear seat in the convertible on both sides Underneath the seat. Where is the water coming from most likely I feel that if I stop the water from getting in under the rear seat that I won’t have any more problems.