Our icebox drain goes to a hose that ends just behind the companionway steps. I could leave the cap off the end and it'd just drain into the bilge. But I don't like water in the bilge, so I leave it stoppered. When I want to drain it, I drain it into a bucket and empty the latter over the side. (The water from two bags of ice requires two trips.) I plan someday to look to plumbing that drain into the sink drain if I can. (Might not be able to do that, as I suspect the bottom of the icebox is below the waterline.) If I do it, I'll probably put a valve in it. Cold water is better than no cooling at all.