where did the water come from?

I have a 79 mercruiser 140hp. I had a problem with water in the engine, but it turned out to be weather.(haven't had any since), I just completed the winterizing on the boat and pulled the outdrive. When it came off, there was quite a bit of water the poured out around the u-joints. This is my first time pulling an outdrive off and I know that there shouldn't be water around the u-joints as water doesn't make for a good lubricant, my question is, where could it possible come from? Any replies would be greatly appreciated. thanks
if you want to know about my water problem, check under milky oil in the gas engines section