Tunnel vision. That’s what it took to create this marvel. Fort Stony Batter Tunnels on Waiheke Island. It’s a testament to human ingenuity. It’s a relic of a time when war loomed large.
Fort Stony Batter Tunnels is a World War II coastal defence fortress. Its location was chosen for a strategic advantage. It has an uninterrupted view of the Hauraki Gulf. It also overlooks the shipping approach to Auckland city.
Commissioned in 1942, the complex has 1.2 km of subterranean passages. These passages include chambers and stairwells. They were all tunneled by hand. The fortress was designed to withstand direct enemy bombardment. It remains in a very high state of preservation. It is an architectural engineering and construction marvel.
Imagine workers toiling in absolute secrecy. They carved these tunnels by hand. The work was slow. It was painstaking. The tunnels became a network beneath the earth.
These tunnels are a tradition among the Waiheke community. For 60 years, they were abandoned and neglected. Locals would adventure into the flooded sections. They would scare themselves silly in the darkness.
The 9.2 inch guns installed in two of the gun pits had ranges of over 30 km. They could fire one round per minute. These were the largest guns ever used in New Zealand. Their mountings could swivel 360 degrees. They could elevate up to 35 degrees. Ammunition storage lockers were in the base of each gun pit. Electric hoists fed them from underground ammunition dumps.
Next to the gun pits, the site contains around a kilometer of tunnels. Most are accessible by guided tour. These tunnels connected the gun pits. They connect the pits with ammunition stores, and a plotting room. An engine room provided electricity. There were also storerooms and barracks above ground.
Construction was delayed for cost reasons until German raiders were sighted. The war entry of Japan turned it into a high priority project. In 1942, the site on Waiheke was chosen. Construction began in October 1943. It was initially thought the battery would take 12 months to complete.
The remote location caused delays. At first, there was no road access. The project was kept secret. The new battery was referred to only as A2.
The tunnels and underground chambers were quarried by hand. Formwork was used for the walls and ceilings. Then, they were filled with concrete. Aggregate was obtained from the rocky outcrops. This gave Stony Batter its name. The tunnels and chambers were designed based on plans of the Tawa Flat railway tunnels project.
The work was completed behind schedule in 1944. The cost ballooned from initial estimates of 140000 pounds to 327966 pounds. By 1945, the threat of war had subsided. Many workers transferred to hydroelectric plants on the Waikato River.
Only two BL 9.2-inch Mk IX X naval guns were installed. One in 1944 and one in 1948. The third gun was cancelled before shipment. They were never fired except for testing and training. The guns were dismantled and sold for scrap in 1961.
Today, a preservation society keeps Fort Stony Batter open. They operate guided tours. The society is trying to source an artillery piece. They want to restore at least one gun pit to its World War II state.
As you explore Fort Stony Batter Tunnels, remember the hands that built it. Consider the world events that prompted its creation. Appreciate the engineering feat. Step back in time within these tunnels.