Traffic was backed up on eastbound Interstate 90 between Mercer Island and Seattle after a canoe capsized along the south side of the bridge on Oct. 18.
The two people in the canoe were close enough to I-90 that they climbed out of the water and onto the bridge deck using an emergency ladder, said Jeff Magnan, services commander for the Mercer Island Police Department. They were both wearing life jackets.
The right lane was closed to traffic as medics and firefighters examined the boaters, according to the Washington State Patrol. The Washington State Department of Transportation (WSDOT) also assisted, Magnan said.
The boat, which was barely visible in the water, was thought to be a kayak or row boat.
Magnan said one of the boaters was in his 50s, and had decided to canoe across Lake Washington, from Seattle to Mercer Island, with his 15 year-old son.
A Mercer Island Marine Patrol unit arrived to retrieve the swamped canoe and other personal property.
The boaters, who were uninjured, were taken to the Mercer Island Boat Launch.