Military Hydrographer Day, also known as Naval Hydrographer Day or Russian Hydrographic Service Day, is observed in Russia every October 13. Established in 1997 by the Commander-in-Chief of the Russian Navy, this professional holiday honors military personnel, veterans, conscripts, and civilian staff of the Russian Hydrographic Service. The day commemorates the founding of the Russian Hydrographic Service on October 13, 1827, which is responsible for ensuring safe navigation through oceanographic and hydrographic surveys, creating navigational maps, and maintaining navigational aids. Celebrations typically include congratulations from high-ranking officials, such as the Commander-in-Chief of the Russian Navy, and various festive events. The roots of hydrography in Russia date back to the reign of Peter the Great, with significant developments occurring over the centuries, including the establishment of the Office of Hydrographer General in the Naval Ministry.