In January 1700, a massive tsunami struck the shores of Japan without any preceding earthquake. Villagers were caught off guard as the sea suddenly receded and then roared back in towering waves. With no shaking felt, the Japanese called it an “orphan tsunami” — a wave with no apparent parent. Centuries later, scientists discovered the origin of that mysterious tsunami across the Pacific Ocean. Along the coastlines of what is now Washington, Oregon, and British Columbia, Native American oral histories told of a night when the earth shook violently and whole villages were swallowed by the sea. Geological studies confirmed the stories: a magnitude 9.0 megathrust earthquake along the Cascadia Subduction Zone had struck on January 26, 1700, triggering a massive tsunami that crossed the ocean and hit Japan ten hours later. This event—known today as the 1700 Cascadia Earthquake and Tsunami—was one of the most powerful in history. And with Cascadia’s cycle of megaquakes occurring every 300–500 years, scientists warn that the next one is due. The Orphan Tsunami of 1700 isn’t just a mystery solved — it’s a warning from the past to the present: the wave that once connected continents may one day return.