I took a ride around Lake Washington on my bike.  Once you have turned north at Renton, you go inland for a short time before coming back to the lake shore at the entrance to Seward Park.  Between Seward Park on the shoreline is Andrews Bay.  Apparently, this is a popular place for boaters to come and hang out on weekends.  It was like a traffic jam there.  Plenty of the boats were tied together with parties underway.  I only had my phone with me so not a detailed shot but it does give a good impression of just how busy the water was.