Apparently the underwater light was not sealed completely. The factory drilled hole is very close to the size of the fixture and has to be carefully closed up. Water travelled through the structure until it found a way out.
In this picture, you see 3 compartments aft of the stern storage area (on the I/O version of the boat, this is the engine compartment). The leak is shown on the stringer that separates the compartment on the left from the larger, center one. The stringer extends back from these openings and is...
This is the joint between starboard stringer and bulkhead under swim platform where the starboard engine is mounted.
No water present in the cavity that houses the motor mountings ... only evident in the discolored area at the joint below those cavities on both sides of the stringer but more...