Hanthorn Cannery was built on a small rock that projects from the sand of the river bottom.  Less than 100 yards out into the river is small buoy that marks the wreck of the Silvie de Grasse,  on another similar rock. According to historic records, this was a 140-foot packet ship, built in 1833 in Hartford, Connecticut for the Old (later called Union) Line of sailing packets that traveled between New York and Le Havre, France. It was sold in 1848 and sailed around Cape Horn carrying miners and trade goods to the San Francisco gold rush.

In November 1849, with owner Capt. William Gray at the helm, she sailed down the Columbia River loaded with a half a million feet of lumber bound for San Francisco, and anchored off Astoria to await a pilot. Once the pilot came aboard, the ship weighed anchor, but a bit prematurely, as the crew had not yet set any canvas. The ship drifted right into a ledge off Tongue Point and got stuck. Normally, a change of tide would make re-floating possible, but Gray had so overloaded his ship that when she shifted, she wedged herself in even tighter. This was very bad luck for Captain Gray, as time was of the essence to take advantage of the inflated Gold Rush prices for his cargo in San Francisco.

He managed to offload most of the lumber, but the ship could not be moved, and she remained irretrievably stuck on the rocks. As of 1869, according to The Overland Monthly, the Sylvie de Grasse was still visible on that ledge, sporting a headless figurehead. The “forecastle … is now overgrown with moss and waving grass,” and “the starboard side of the quarter-deck … is marked by a luxuriant bunch of alders just peering above the taffrail.” By 1895, her frame timbers could only be seen at low tide. Remnants of the ship are still there on the bottom where some daring scuba divers operating from the pier have inspected them.