The image below is a side scan image showing two section of the old I-90 floating bridge. This bridge sank in 1990 during a severe rainstorm over Thanksgiving. The bridge was closed at the time of the sinking and undergoing renovations. Some sections of the bridge resting on the Seattle side of the lake used to be popular for diving. However those sections of the bridge are actually under the new bridge and the Department of Transportation sighting Homeland Security concerns has now closed the site to divers.
Hopefully they will reconsider this decision in the near future. Unfortunately these images were obtain traveling along the set-back boundary scanning in towards the new bridge so these sections are also within the enforced no access section and off limits to exploration by divers.
You will note these images have several wavy sections within them. This is caused by the boat moving to maintain position. There were strong winds this day hitting the boat broadside making it difficult to hold position. The police boat floating next to us ensuring we did not drift across the set back boundary obviously took priority. Shaun Gardner did an excellent job captaining the boat.