The walk follows the fence line down to the old railway formation, which leads to the 250-metre tunnel. Walk through to follow the tracks to a picnic area overlooking the local farmland and scenery.
The carpark and track entrance are signposted on SH92, the Southern Scenic Route. It's 5 km north of Owaka.
Tunnel Hill was built as a part of the Catlins River Branch railway which formed a part of New Zealand’s national rail network. It was built mainly to provide access to timber for logging companies. The railway was built in sections between 1879 and 1915 with the majority closing in 1971, including the Tunnel Hill section.
This historic reserve preserves a tunnel on the old Catlins River Railway. The line’s construction, using handmade local bricks, began at Balclutha in 1879. This tunnel section was completed in 1896 and the line reached Owaka a year later.