Digger Tunnel

The Digger Tunnels are large caves opened up by the Hag 1 digging drill while on its way to the Cauldron Keep in Banjo-Tooie. Klungo engages Banjo and Kazooie inside the each of tunnels for the first two of the three battles with him. When they get through the gate, The gate will close after a word from Klungo. Once the battle has been won, the gates open. The tunnels cannot be reentered after they leave the tunnel.

Since the tread marks from Hag 1 lead straight through the caves rather than all around inside them, it can be inferred that the caves were not created by Hag 1 and were merely tapped into.

Inside the Digger Tunnel
This is where Hag 1 has dug through the mountain from Jinjo Village to Spiral Mountain. The first battle Banjo and Kazooie have with Klungo takes place here. It can only be accessed the first time Banjo and Kazooie go through the entrance from Spiral Mountain to Jinjo Village. He uses either-invisibility,prototypes or increased sized.

Inside Another Digger Tunnel
This is where Hag 1 has dug under the pond in Pine Grove from the Wasteland. The second battle with Klungo takes place here. This entrance is blocked by a Talon Torpedo Door.

Trivia

 * It is only possible for any character in the digger tunnel with an instant wrap code on Project64. Klungo cannot be beaten by any character even if Banjo and Kazooie are separate.
 * If the Unlimited Travel code is activated using Gameshark, Digger Tunnels can be re-entered sans the titles appearing on the screen upon entering it.
 * Bottles' Revenge Mode cannot be used if they enter the conversation and boss fight with Klungo.
 * Mumbo Jumbo will only want to leave 1 way out of the 1st digger tunnel.
 * Humba Wumba will not let the transforminations out of the 2nd digger tunnel if entered by different character transforminations.
 * Banjo or Kazooie alone cannot leave the digger tunnel to get somewhere else.