This article contains information that relates to the non-canon game Pikmin: Ultimate Doom by Wraith.
Sand Fortress is the third area on Pikmin: Ultimate Doom and a large-scale sand castle. The landing site is near the bottom at the entrance to the sand castle. It's on top of the drawbridge over a moat of endless height. Inside the castle lies four floors. The bottom floor has multiple Sandy Burrow-Nits and one Burrowing Snagret. One cave is on the first floor, Watery Catacombs, along with two treasures, the Collaborative Cloth and Dedicatee's Stone, one of which is in water. On the second floor has the Blue Pikmin Onion. It is cleverly guarded by several Sand Bloysters. When the one with a golden torso is killed, the only treasure of the floor, the Arid Remover, will emerge and the walls around the Blue Pikmin's wild Onion site will fall. The Blue onion is in a watery hole, so dismissing the other Pikmin is a wise strategy. There is one cave on the second floor, Dune Gulch. The third floor holds two treasures. A Spotty Bulbear dominates and scours the area with four following Dwarf Bulbears. There are many puddles of water on this floor, which gives the Bulbear an advantage as it camps in the pools of liquid. Floor four has one treasure, the Rampant Guise. It's devoid of enemies but is filled with water.
After returning from the Space Station, Olimar and Louie get out of the Trailblazer, ready for another day's work. Olimar mulls over what Apollo said, thinking deeply about why he is using the Pikmin for such greedy reasons. Thinker chimes in. "We have found a distinct biological pattern similar to that of the Onions, and with visual scans I can confirm that there is indeed a Blue Onion inside the structure. Once you acquire Blue Pikmin, you need to give one up for testing. We will know so much more about Pikmin once this task is complete. Also, Hocotate Franchise has surpassed the Mayor's Office in Pokos. It is now the most wealthy organization on all of Hocotate. Interesting. Okay, back to work!"
When Olimar and Louie find the wild Blue Onion, Olimar signals for a Blue Pikmin and puts it into the Trailblazer's cargo pod. He nods at it and sends it off, looking away in disappointment. Louie rubs his helmet, feeling the ever-deeper crack, and turns around. The two return to work with the new Blue Pikmin.
After treasures and caves
Once the player has collected every treasure and cleared every cave, Thinker will speak again. "Hello again, Olimar. I see that this area is cleared, good job. The space station summoned you and Louie, you might want to go up there. Also, they will brief you on the findings with the Blue Pikmin as well. See ya!" Olimar and Louie will go up to orbit, prepping for dock with the space station.