G-Base

You'll be able to tell when you're nearing this important dungeon in the Penumbra Plains because you'll start encountering more and more loan shark defense systems and scrap metal as you approach it. The direct area around it is even surrounded with voltage spires, which can prove to be very annoying. Also keep on the lookout for things like G-Pods and Drilling Digger machines. You should enter with a highly diverse and able force to rescue the President at the bottom of the dig site.

Obstacles

 * Voltage spire

By the end of the dungeon, it'll become apparent that the loan sharks aren't behind it all- it's merely just a bunch of loan shark equipment that got scrapped and left behind on the Pikmin planet after being thrown out in space. But then, who started up all these machines again? Why are they digging in the Penumbra Plains? The spread of spores through Puffstools seems to be controlling the machines. Somebody wanted you to get those Dark Spores so they could use them for their own purposes! The largest and final one is in the Penumbra Plains at the bottom of the Black Hole. That's where you should head for next to make sure it doesn't fall into the wrong hands.