How do you get through Drill Tunnel?

To get through Drill Tunnel (if you mean the one in the underground lake) you have to defeat Drigomemon in the residential area and then talk to the Drigomemon in the underground lake and offer to carry dirt.

When you have got rid of all the dirt, leave the screen, leave the underground lake and re-enter. Go back to where the Drigomemon was, and you will find he will have hit a big rock. (You need a champion Digimon to move the rock.)

If you mean that one thats always singing "today we'll be digging..." get 45 proposerty rate and go to where he is. (a clue is there is wires everywhere) go into the hole he makes and you'll find a computer and leomon's tablet. (you'll find Nanimon next to the tablet later in the game).

If you want to go to Lava Cave through Drill Tunnel carry the Dirt 10 times after fighting the Drimogemon who was rolling because of the heat then go out Of the Underground Lake then enter again to find the path open and continue your exploring there.

If you want to go throught the Third Floor of Drill Tunnel where Drimogemon is always digging get 45 prosperity rate then go to him to find that he finally dug the path then enter and complete your exploring and I will leave it a surprise for you.

If you want to go through the path of Mt.Panorama without passing through Drill Tunnel then go to the Foot Of Mt Panorama and then go to the south east to find a tunnel go into it and talk to the Drimogemon to join the city and you may pass through it anytime without disturbing yourself and wasting your time.