Drunk boating killed a high school classmate of mine, in front of his oldest grandchild no less. He was a massively talented musician, specializing in arena rock, and his brother was eventually arrested.
There was also a double (let's call it what it is) murder in my area more recently, where a boat occupied by a middle-aged couple, a real estate developer and his OB/GYN fiancee, was run over by a bigger boat piloted by an underage drunk. Because the pilot's parents were even wealthier than the victims, they got away with it, but thankfully their parents did not, in the long run.
Getting on a boat while intoxicated on anything is probably MORE dangerous than impaired driving.