Consider the size of the Strait of Juan de Fuca. It enters from the Pacific Ocean around the southern tip of Victoria Island (from 12 to 25 miles wide and up to 330 feet deep), up Haro Strait in the Salish Sea with a very strong current, to Boundary Passage. Then with only 3 miles separating East Point on Saturna Island in Canada, and Patos Island in the United States, and the depth of the channel between the two at less than 200 feet, it is easy to see why the constricted point causes very fast and erratic currents. Boiling Reef northeast of the eastern tip of Saturna and the reef around the north and west of Patos only restricts further and adds to the water’s confusion. Tide rips occur both north and west of Patos. To the east of Patos are more islands and the water is much shallower, and less water passes. Mud and silt from the Frasier River settles in the bays here.
The Strait of Georgia, beginning on the north side of Patos, also has very treacherous waters. Shipping moving from the north had to deal with whirlpools and tide rips, and fast-moving waters. It is 150 miles long and 12 to 36 miles wide with a mean depth between 512 to over 1,380 feet deep. The cold denser deep water moves in one direction, while the upper warmer layer of water moves in the opposite direction. In addition, there are upwellings, where the nutrient rich bottom layers rise to the surface, providing food for baleen whales and many smaller water dwellers, at the same time creating more water disturbances. Just immediately north of Patos Island there are large sand dunes with north-pointing caps deep beneath the surface that cause the whirlpools. They point north because of all the water flowing north from Boundary Pass, only 2/3 of it returns. The other 1/3 continues north with the north-moving tides.
Tumbo Point also has a reef heading northeast, where the coal-filled John Rosenfeld wrecked in 1886, only a few miles from Patos. Earlier, in 1872, the Zephyr ran onto a reef off Mayne Island, just a bit further to the northwest, also near Patos. It was carrying 2 sandstone columns from a quarry on Newcastle Island for the new San Francisco Mint. Both wrecks received widespread publicity and were very costly in terms of lost lives and value of the cargo.
In the late 18th century Juan Pantoja y Arriaga, a Spanish explorer, navigator and cartographer with Francisco Eliza recorded that the waters around the southwest point of Patos were very treacherous, with “such whirlpools that without exaggeration there seems to be a small vortex.” Since this time the dangers to navigation through this channel were known. However, it was not until 1855 when our young and growing nation built the first west coast lighthouses on Alcatraz Island in San Francisco Bay and Point Pinos, at Pacific Grove, California. While the gold rush burgeoning population continued to hammer for lighthouses to protect the valuable shipping industry, it was not until 1875 when the boundary dispute with England was resolved that the federal government withdrew the island from settlement as a potential aid to navigation.
The withdrawal was made possible when the German Chancellor determined the line demarcating the division between the US and Canada, and Patos fell on the American side. Still, warnings about the hazardous circumstances continued. The Vancouver Island Pilot told mariners that Boundary Passage “was subject to heavy tide rippling and eddies.” And the United States Coast Pilot agreed that “heavy dangerous tide rips occur between East Point and Patos Island and for two miles northward in the Georgia Strait.” A full century after Juan Pantoja de Arriaga issued the navigational warning, in 1891 the engineer George Freeman surveyed Patos, and selected a spot where the lighthouse should be.