Check out this 1984 Sea Ray 340 Sundancer that we installed underwater lights that illuminate the water 360 degrees around the boat!  
We love underwater lights and we know how to properly install them for a clean and water tight installation. Usually these lights will create what I call your very own fish tank under your boat. Fish, mainly bait fish, are attracted to the lights and the bigger fish will surface to feed on the bait fish and will swim around all night until you shut them off. Kids and fishing men & women especially love this experience. White color seems to work the best but other colors will work as well. The best type of LED to have installed would be a RGB type LED with a controller. That way you can change the color to any color you desire. Usually a choice of 16 million different colors.  
We have 12 years of problem free experience with these installations. We know what you need, if you want the best and what you can get away with,
if you're on a budget.