This thing was moving Northabout as fast as a small airplane but it appeared to be tumbling and not traveling in straight line.

I was inside the Mukilteo ferry terminal when I saw a dark object moving North over South Whidbey Island. That is about 3.5 miles from where I was. It was probably 500 to 800 ft above the Island. After watching it for a few seconds I could see that it was not an airplane. There were no wings or tail and it appeared to be tumbling as it moved forward. I alerted a young lady that was there and she snapped these shots. At that point it had made an arcing turn to NE and was about over Hat Island when took them. Unfortunately when you zoom in they get blurry. It then continued in the direction of the Tulalip reservation and disappeared.