there are two for lake union, the easiest is the 14th street luanch, it is just off of 15th and the street ends into the boat launch, however you will have to travel all the way up the canal into lake union, the second one is east of gasworks park, just keep driving staright past itand there will be parking spaces on your left and the launch to your right(this is if you are coming from the west) the only one i have been to that is actually on lk washington is the magnuson park boat luanch, it is on the west side of the lake a little ways north of the 520 bridge. soryy the direction aren't too exact but hopefully it will give you a start, good luck!