From Seattle, drive north about on I-5 for about 93 miles then take 542 East for about 60 miles to the Mt. Baker Sky area. From there you can park along the edge of the lake and enjoy the view.
Be careful with nature, lots of meadows with pristine, delicate plants. Since it is quite a drive, plan for a hike in the area or if wintertime, snowshoe to artist point.
Picture Lake is one of the most picturesque places on the American continent. Located north of Seattle, Washington, very close to the Canadian border, Picture Lake with Mt. Shuksan in the background has attracted photographers to these places over time, due to easy access and opportunities to capture the beauty of the area year-round. On this occasion, my goal was to take some photos of the Milky Way over Mt. Shuksan. I took a few shots during the night, only to return the next day very early in the morning for some sunrise shots. It was worth it!