The 8.5-kilometer-long Ōtira Tunnel opened in 1923 and travels through the Southern Alps, completing the Christchurch to Greymouth rail link.
Although the rail tunnel is now only the third longest in the country, it remains an engineering marvel. During its construction, tunnelers contended with harsh conditions, using basic tools to drive through wet shale and rotten rock, and with the steep track grade required (ascending 1 in 33 from Ōtira to Arthur’s Pass).
