Like Rowdy said, most likely coming from the outdrive. Depending on what kind you have, the older omc sterndrives had one large boot, and the mercruisers may have up to three hoses, for the shift cable, exhaust, water intake, etc. One thing I learned the hard way, I just had mine replaced was not to leave the motor trimmed up when in storage. This places unnecessary strain and causes premature failure on these parts.