Digger Tunnel

The Digger Tunnels are large tunnels dug by the Hag 1 while heading to the Cauldron Keep in Banjo-Tooie.

Banjo-Tooie
In Banjo-Tooie, Klungo is first fought Inside the Digger Tunnel that connects Spiral Mountain and Jinjo Village. He is later found again Inside Another Digger Tunnel that connects the Pine Grove and the Wasteland, although the Talon Torpedo move is required to access it. Burgers and Fries obtained from Witchyworld however will be confiscated if this tunnel is used.

Once Klungo is beaten inside a Digger Tunnel, it cannot be re-entered, and attempting to do so will simply take Banjo and Kazooie to its other side.

Banjo-Kazooie: Nuts & Bolts
In Banjo-Kazooie: Nuts & Bolts, the first Digger Tunnel can be seen in Spiral Mountain, although it is blocked by rocks. An Information Speaker also provides information about it, stating it once led to the Isle O' Hags.