Manuel seems to have spotted a sunken jet near the Renton Boeing plant.

In January, a 737 was sunk to create a divers’ reef near Vancouver Island.

Could this be the PBM-5 that was supposed to be raised about 10 years ago? It looks about the right size. However, the wing profile of the possible plane Manuel found seems more like a jet than a prop plane.

Here is a page on plane wrecks in Lake Washington. The Submerged Cultural Resources Exploration Team maintains a list of dives in the lake; no jet appears among them.