Chemical Lake

Chemical Lake is the second area on Duron in Pikmin: Ultimate Doom. It is a large rolling jungle plateau of dirt and rock, with a lake at its foot. It is so rugged that Olimar has to reach it by foot to make a landing zone. Contrary to the name, the terrain is polluted by acidic chemicals, not the lake itself. Green Pikmin are found here from Leafy Candypop Buds above ground. As Green Pikmin don't have an Onion, they are stored in the Trailblazer.

Story
Louie stumbles onto an ancient tablet relating to rips in reality, and the trail leads underground. So Louie and his Pikmin venture to Acid Cave while Olimar and Pikmin collect twenty water packets. When both tasks are fulfilled, Louie returns with the Relic Amulet. It has a location engraved on it: a desert with more ancient tablets, Deathbone Desert.

Caves

 * 1) Acid Cave