water around fish hold.

Have the tank out and while prepping the fuel void noticed some water weeping into the void around the drain tube that goes under the fish hold from the front under the floor, I removed an old screw that was used to hold a pump or something on the aft wall of the fish hold and got water comming out under pressure.
let it do its thing and I pumped out 3. 5 Gal buckets from the fish hold.
Any ideas on where this water entered from?
The fish hold appears to be a premade tub that was set in before the deck went on and the plywood wall of the fuel void was dry. Soooo ?

Can't help, but please let us know your findings....