It's often tempting to show waterfront property by boat - both for the lifestyle experience of being out in a boat, and to see the properties from the water side, and check the docking facilities and the water depth. There are a few things to check out first, though:
Does your boat insurance cover it's use in business? If you take people out to look at or show properties, that's a business use.
Do you need a captain's license? As long as your passengers are not paying for the ride, you may not - but check the regulations in your area to be sure.
While you may want to use your own boat to show property, you might want to check into hiring a captain and a chartered boat.

I love boating it's how I like to spend my sparetime her in South Florida. I think it's a good idea if you want to show a client different waterfront communities, it might be too time consuming to show many properties in one day though.
Michael - that's interesting. Almost all the homes here have boat docks, except those directly on the Gulf of Mexico.
Leo - even a few of the developers will take you on a boat ride.
Scott - you also have to consider tthe buyers may not have a clue how to dock a boat or assist you.