Amagi Tunnel
The Amagi Tunnel (Amagi Tonneru) is a tunnel that runs through Mount Amagi via the Japan National Route 414 from Izu to Shizuoka, Shizuoka under Amagi Pass. There are two tunnels, the Amagi-san Tunnel, which is the Old Amagi Tunnel, and the new Amagi Tunnel, also called the Shin-Amagi Tunnel.
Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).