Watching Torpedoes From the Summit
The Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post (旧佐世保海軍工廠川棚魚雷遠距離発射場観測所) is a two-story brick and reinforced concrete lookout built in 1925 on the southern summit of Katashima in Kawatana, Nagasaki Prefecture, and registered as a Registered Tangible Cultural Property of Japan on August 15, 2024. With a building area of 19 square meters, it is where observers followed the wake of each torpedo fired from the platform below.
A lookout stood here from the start of the range in 1918: a single-story timber hut of about three tsubo (roughly the size of six tatami mats), known as the No. 1 Watchtower. In 1925 it was rebuilt in brick and concrete and renamed the Observation Post, and the two watchtowers across the bay at Takashima and Kazehaya each moved up a number.
At the end of the war the interior partitions, openings and second floor were destroyed. The outer walls and the roof survived.
Function Made Visible
The Agency for Cultural Affairs praises the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post for an exterior that turns its function directly into form. Reinforced concrete beams and a slab wrap the top of two stories of brick walls, and on the south side a triangular observation window juts out from the second floor.
The triangle is there to widen the view. A window set flat in a wall sees straight ahead; one pushed out to a point sweeps left and right, so observers could keep a torpedo in sight even when it veered off course. The reason for the shape is written on the outside of the building.
The walls are brick finished with mortar, while the projecting window and the floor slabs are reinforced concrete. Inside, the lower walls were mortared and the upper walls plastered.
A Roof Ahead of Its Time
The roof of the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post is a reinforced concrete slab with a raised parapet and a drainage gutter around the edge. Its waterproof mortar is jointed about every 1 meter, much as modern flat roofs are detailed, and Kawatana's preservation plan points to it as evidence of how capable the concrete work was.
Time is catching up, though. Part of the roof slab has sagged and lets rain in, the floor of the window projection is damaged, and in places the rebar is exposed and rusting. Graffiti has stained and gouged the walls.
The town's plan aims to keep the building as it was when registered, but makes an exception for the sagging roof, since leaks would speed its decay. Rust treatment for the rebar and removal of graffiti are also scheduled.
Visiting the Summit
The Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post stands inside Katashima Park on the island's southern summit, reached by a path climbing through the woods, and can be viewed free of charge. The national database's main photograph shows the southeast face, the best side for seeing the triangular window.
The second floor no longer exists, so you cannot go upstairs. The ground is uneven; wear sturdy shoes. Keep out of any signposted areas and do not touch or mark the walls.
From the top you can take in the sweep of Omura Bay where the torpedoes ran. Directions to Katashima Park and general visiting information are gathered on the page for the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range as a whole.
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Q&A
- Where is the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post?
- Inside Katashima Park, on the southern summit of the island, at the top of a path through the woods.
- Can you go up to the second floor of the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post?
- No. The second floor was destroyed at the end of the war and no longer exists. The exterior can be viewed freely.
- When was the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post built?
- In 1925, replacing the timber No. 1 Watchtower that had stood on the summit since 1918.
- Why does the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post have a triangular window?
- The projecting triangle widened the field of view so observers could track torpedoes across the bay, even when they strayed off course.
- When was the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post registered as a cultural property?
- On August 15, 2024, together with the firing platform and three other structures of the range.
Basic Information
| Name | Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post |
|---|---|
| Location | 174 Katashima, Mitsukoshi-go, Kawatana-cho, Higashisonogi-gun, Nagasaki Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered 2024/8/15 (Reiwa 6) |
| Quantity | 1 building |
| Dimensions | Brick and reinforced concrete, 2 stories, building area 19 square meters |
| Owner | Kawatana Town |
| Public Access | Inside Katashima Park; exterior viewable freely, no fee. Second floor not accessible |
References
- Agency for Cultural Affairs, Database of National Cultural Properties: Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00015110
- Kawatana Town: Preservation and Use Plan for the Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range (Japanese)
- https://www.kawatana.jp/cat03/c3-03/post_732/index.html
- Kawatana Town Tourism Guide: Torpedo Launch Test Site (Japanese)
- https://www.kawatana.jp/kankou/2010/12/post-24.html
- Cultural Heritage Online: Former Sasebo Naval Arsenal Kawatana Long-Range Torpedo Firing Range Observation Post (Japanese)
- https://bunka.nii.ac.jp/heritages/detail/564168
Last verified: 2026.09.25
