Even on Lake Superior, the largest of the Great Lakes of North America, the tiny effect of a tide is overcome by the effect of barometric pressure and the phenomenon known as a seiche. There are no Tide Tables of the Great Lakes and seiche warnings are rarely broadcast, as most cause a variance of less than 50 cm.

Technically, Lake Superior (and all of the Great Lakes) does have a tide, but it is so minuscule that it is considered "negligible" and is completely masked by other natural forces. The "true" astronomical tide—caused by the gravitational pull of the moon and sun—results in a water level change of less than 2 inches (5 centimeters) on Lake Superior. In contrast, oceanic tides can vary by dozens of feet. Because the lake is "small" compared to the vast oceans, the gravitational difference from one side of the lake to the other isn't strong enough to create a significant tidal bulge. Instead of a tide, Lake Superior experiences a phenomenon called a "Seiche" (pronounced saysh). A seiche is a "standing wave" caused by changes in atmospheric pressure or strong winds that "push" the water to one end of the lake; when the wind stops, the water sloshes back and forth, creating water level changes of several feet in just a few hours. To a casual observer, a seiche looks like a tide, but it is actually a weather-driven oscillation rather than a moon-driven one, which is why Lake Superior is often called a "tideless" sea.