Born into a farming family in Tsukuba District, Hitachi Province (Ibaraki Prefecture), Mamiya Rinzo developed an interest in surveying and traveled to Ezo (Hokkaido) as a hired surveyor for the shogunate. Working alongside Ino Tadataka's survey team, he mastered precise surveying techniques. Between 1808 and 1809 he twice explored Sakhalin alone, traversing to the island's northern tip and confirming that Sakhalin was an island separated from the mainland by a strait. The strait he crossed while surveying the northern coast was later named the "Mamiya Strait" (Strait of Tartary) by Siebold and marked on world maps. He became one of the rare Japanese explorers known internationally by name. After returning, he served the shogunate for many years in defense and surveying work in Ezo and the Kuril Islands. Acclaimed as the "foremost expert in cold-region exploration," he is also said to have worked as a shogunate spy in his later years, making him a figure of considerable mystery. His exploration record "Journey to the Eastern Tartar Lands" is an important document in the history of geography, and Mamiya's achievements became the foundation of post-Meiji northern territorial policy.