The Underground is the eighth level in The Keys of Krodacia. As the name implies, almost the entire level is underground. Other than the Krodacian temples, this is the only level where there are temple walls located in various parts of the underground tunnels. As the Brombos enjoyed being on the cliffs, it seems a lot of Patsy and the Slurples enjoy being underground, because there are many of them located here. You will also find Magiflies (on Hard difficulty.) Keen will need to do the usual tasks in order to complete the level and find the next key to the Universal Toaster Canon.
There are a total of 44,200 points "underground", meaning 42 Krodacian Sodas, 50 Blue Peppermints, 12 Chocolate Bars, 2 Sugar Cubes, 6 Burgers and 2 Strawberry Jellos (4,200 + 10,000 + 6,000 + 2,000 + 12,000 + 10,000 = 44,200). The total of gems is 58. There's a single 1-UP hidden in a secret alcove.