Yokotone Lock, Navigation lock in Inashiki, Japan

Yokotone Lock (横利根閘門) is a brick lock on the Yokotone River at the Ibaraki–Chiba border, completed in 1921. It is a double-chamber, double-gate lock with a usable length of 90.9 m, width 10.9 m and depth 2.6 m below the mean low water level. The lock chamber has concrete block paving and sloped sides with wooden fenders, while the gate rooms are concrete with brick and stone facing.

The lock was constructed in 1921 as a major advancement in Japanese water management infrastructure during the early 20th century. It formed part of Japan's broader modernization of transportation systems in that period.

Locals call the lock "kanmon," and the surrounding Yokotone Lock Fureai Park, managed by Katori and Inashiki, was chosen as one of Japan's 100 Historic Parks in 2006. The park is known for cherry blossoms and fishing along the Yokotone River. The lock sits at the border of Ibaraki and Chiba prefectures, though the structure itself is in Inashiki.

You can watch the lock in operation from the riverbank when vessels pass through. The best viewing spots are located along the sides of the structure where you have a clear view of the entire operation from start to finish.

The lock's gates are mitre gates: four large and four small steel leaves, each built from plates riveted to five vertical and two horizontal girders. Originally cranked by hand with rack bars, they are now opened and closed electrically from a control panel.