This is a large underground region. Unlike the previous area, you can explore nearly all of it without breaking out any barriors first. You don't even need to break down all the barriors to get all the parts here, but the shortcuts you create may save time in the long run.
The Blue onion is in this area, bur growing their population to a useful number will take some time. We will cover the onion and the easier parts here, and the more difficult parts in a separate page later in the walkthrough.
We'll cover this first not because you should do it first but because the opportunity to get it could come at any time and you'll want to be ready. There's a creature wandering around this region which looks something like a dinner roll and is aptly named the breadbug. It makes a distinctive sound when it walks so the chances are you will hear it coming before you see it. Its one mission in life is to find stray food pellets and bring them back to its nest. It has a tough hide and Pikmin won't even bother to attack it, though you can damage it a small amount by throwing a Pikmin on top of it or by hitting it yourself. The problem is that it has somehow swallowed a ship part so you must defeat it some how. The trick is to wait for it grab a pellet and throw two Pikmin at it (one won't be enough). The Pikmin, carrying the pellet to an onion, will overpower the breadbug and when the pellet gets sucked into the ship the breadbug will nearly be killed. Either repeat, throw Pikmin on it or hit it yourself to finish it off and out will pop the Space Float. This is an optional part.
The Blue onion
You may notice the Blue onion sitting in a pool to the west of the ship, but before going over there it's a good idea to draw some Pikmin from the other onions and start them working on other things so they're not idle while you're trying grow Blue Pikmin. The most immediately useful things to do are to break down the lattice wall north of the ship and to build two bridges south of the ship.
Find the Blue onion; it's marked on the map. You know the drill by now; it turns bright Blue and ejects a seed when you approach and this time you get a Blue Pikmin when you pluck the sprout. From the fact that the onion is sitting in a pool of water you might guess that the special ability for this color is that they can survive in water. This may not seem like a big deal but there is a lot of water in the game so it's useful to have a large number of Blues on hand. In contrast, while the role of the Yellows is important, you only need to use a few at a time so there's not much use in trying to grow their number beyond what you probably have now.
Use the nearby pellet posies and the food pellet grow your Blues; you should be able to get to 16 from this.
Once you have Blue Pikmin you have everything you need to get any part in the game, though your ship isn't powerful enough to reach new areas yet and you may need to grow additional Pikmin to get certain parts. The point is that the order in which you get the remaining parts is almost completely up to you, so feel free to skip around in this walkthrough according to your own preference. This guide does not attempt to give best order in terms of efficiency, so you may want to experiment with the order to improve your best score on further playthroughs.
#1 Ioniom Jet
If for some reason you haven't already, you will need to break down the lattice wall north of the ship. The only route the Pikmin can take to get the part back is through this barrier. Take at least 15 Blues north west through one pool and into another pool beyond. These are to the right of the pool with the Blue onion (or where it first landed if you're already on a new day). Just send the part off with the Blues and as long as the wall has been cleared they should be able to handle the rest on their own, so you can do something else.
On the shore to the left of the pool you may notice a green can with bomb-rocks. This is one of only two locations in the region where you can find them, which isn't a lot considering how many walls are here. The good news is there are larger numbers of them in this region. To reach this with Yellow you have be careful to always keep them on the shore to the left of the ponds; it's best to limit your party to about 10 Pikmin when doing this. Getting the Yellows back is even trickier though. First throw the Pikmin back to the previous ledge; there's a stick bridge here (see below) but it doesn't really help. Circle around and pick up the Pikmin waiting on the ledge, remembering to touch them, not call them, otherwise they will set off their bombs. Lead the Pikmin to the next ledge up and repeat. You are now within shouting distance of the ship and should be able to find some good targets to use the bombs on.
Take at least 15 Pikmin and head southwest from the ship. A solid wall block the most direct path so it will help to clear it beforehand. You will come to a kind of canyon with some sticks on your side and a gear (the Automatic Gear) on the far side. Start your Pikmin to work on the sticks and they will turn it into a rudimentary bridge. When it's done they will automatically use it to cross the gap and when they land, with nothing else to do, they will start moving the gear. The result will be that the gear and the Pikmin will come crashing down to the floor of the canyon.
While all this is happening, take some additional Pikmin and head for the floor the canyon. This is to clear away a new enemy that's lurking there, shearwigs. They are green in color and are the adult stage of the sheargrubs. They mostly behave similarly, but they are more aggressive fighters and fly when wounded. When this happens throw Pikmin at them to bring them back to earth. The good news here is that even through it only take a single Pikmin to carry one, you get four seeds from it, making them a good way to build up Pikmin numbers.
With the shearwigs out of the way you should be able to send the gear off to the ship with no further trouble.
Take a large party of Reds south from the ship. You will reach a flat area with a pond on the right. This area has another new enemy, fiery blowhogs. They are fat, grey and shoot fire out of their snouts. Fortunately Reds have an ability that we haven't used yet; they are immune to fire. So the worst that the blowhogs can do to them is blow them around, possibly causing them to lose their petals. So just attack them as if they were bulborbs, making sure they're not facing the water when you do or your Pikmin may get blown into it. There is another enemy you may encounter as well if you get too close to the pond, namely wollywogs. This is a grayish frog that attacks by jumping on top of your forces to squish them. The trick to defeating them is to dodge their jump, then swarm them with a large enough force that they can't jump again.
Clear some of the blowhogs out of the way, but our real goal right now is on a ledge on the south side of the flat area, just to the left of the pond. There is bridge leading from the top of ledge down, and you need to throw the Pikmin just right for them to start working on it. This might be easier with Yellows, but running them through the gauntlet of blowhogs won't be pretty. Building the bridge will take a while so you can do something else while they're working. When it's done you'l find the Gravity Jumper on the ledge. Getting it back to the ship may take some supervision since there my still be enemies, but if you've built the two bridges just south of the ship you should be alright once you reach them.
On the far side of the ledge with the gravity jumper is the second source of bomb-rocks in the area. You will need to build another bridge to get the bombs back, and you'll want to make sure the area is well clear of blowhogs, so getting the bomb-rocks isn't easy here either.
This part should be done with the Analog Computer) since their both in the same corner of the region. To get it you will need about 5 Blues, at least 20 Yellows, at least 20 Reds, and additional Pikmin to clear the path. (If you are combining this with the Analog Computer then have at least 20 Blues; see below.) Gather your force and head west, then south through the canyon described in the section on the Automatic Gear. This takes you to the same flat area you needed to cross to get to the Gravity Jumper, but this time we're heading for the right side of the lake. Clear any enemies along the way. There is a passage leading to the right from the lake, but it's blocked by a lattice wall so start your Pikmin working on it. When the wall is down you'll see a path next to a cliff and jets of fire in the middle. Reds are immune to fire so take them in a separate group and start them working on a bridge on the right side. Come back for the Blues and Yellows and use to make sure they hug the wall and avoid the flame. Set the Blues and Yellows to work on the bridge when you reach it. When the bridge is done, cross it, then take your Blues and point them at the small hole in the puddle on the left. They will open up a steam vent for you. You may have noticed these around the region before but this is the first time we've actually needed to use one. Gather your Yellows and throw them to the ledge on the right, then use the steam vent to blow you to the same ledge, and finally throw the Yellow to the next higher ledge where they will start to move the Libra. Don't let them go far with it though; when the Libra is on solid ground call the Yellows away from it and replace them with Reds since only these will be able to survive the fire jets encountered on the way back. Let the Reds carrying the part fend for themselves on the way back, but guide the Blues and Yellows around the fire jets as you did earlier.
This part should be done with the Libra (see above) since their both are in the same corner of the region. You will need at least 20 Blues and 20 Reds and additional Pikmin to clear the way. Follow the directions for the Libra as far as the bridge, but for this part continue along the path until you reach a pool on the left. The Analog Computer is sitting in the pool, so gather your Blues and use them to get the part out of the water. Once it's on dry land, call the Blues away and replace them with Reds since they can safely carry it over the fire jets. Don't forget to lead the Blues around the fire jets on the way back.
If you've done everything we've covered fo far you should have enough parts (12) to go on to the next area. You could also continue on here are go back to finish up one of the previous two areas. Just to prevent this guide from jumping around any more than is necessary, we're going to go back to The Impact Site and continue from there to the end.