Haro Strait is not only a waterway. It is the international boundary, and the line between the United States and Canada runs down the middle of it, which means the water off Turn Point is Washington on one side and British Columbia on the other. Stuart Island is about as far into the archipelago's northwest corner as San Juan County reaches. Beyond the point, the strait opens toward Boundary Pass and the Gulf Islands. Deep-draft traffic bound for and from the ports of the Salish Sea threads through here, and the geometry of the passage is unforgiving: a narrowing channel, strong tidal streams, frequent fog and a mandatory change of heading, all in the same place. Light stations exist where the consequences of error concentrate, and this is one of those places.

The keeper's house dates to 1893, and it is still standing. Consider what the posting involved. The light had to burn every night without exception, which meant a keeper present every night without exception, on a point at the end of an island with no road to anywhere. Supplies came by boat and only by boat. Weather that closed the strait closed the household along with it. In fog, the light was not enough and the station's fog signal had to run, which in the nineteenth century meant machinery that had to be started, fed and watched by hand, sometimes for days. The isolation of a station like this is not a romantic detail. It was the job description.

The station was electrified in 1925, and the way it happened is quietly perfect. Generators were installed in the fog-signal building, in the very room that had until then stored coal for the old hot-air engines. The fuel of one era moved out and the machinery of the next moved in, into the same square of floor. The new generators supplied the navigation light and also the lightkeeper's house, which meant that for the first time the family living at the end of Stuart Island had electric light indoors. It is easy to read the electrification of a remote station purely as a technical upgrade. For the people who lived there it was something closer to a change in the quality of ordinary evenings.

In 1936 a square concrete tower was added to the site, carrying a 300-millimetre light at a focal plane of forty-four feet. Those numbers look modest, and they are, deliberately. A focal plane is the height of the light above the water, and the right height is not the greatest possible one: a light set too high can be lost in low cloud, while one set appropriately for a close-range turning mark shows exactly where it is needed. Turn Point does not need to be seen from enormous distance. It needs to be unmistakable to a ship that is about to change course, at the moment that ship commits to the turn.

The station today is open to those who make the effort to reach it. Volunteer docents lead seasonal guided tours of the original 1893 keeper's house, and the fog signal building holds a small museum on the history of the light station itself. The oil storage building has been given over to a different subject entirely: the orcas that frequent the waters off the point. It is a fitting reassignment. The same channel that made a light necessary, deep and swift and funnelling everything through a narrow gap, is also what brings the whales past, and visitors who come for the lighthouse frequently find themselves watching the strait instead.