The next upgrade takes you to an underwater section of Torvus. The upgrade is used underwater, but since there aren't really any underwater areas outside Torvus, it's not as useful as you might hope.
Get to the lower part of Torvus Temple, and go through the Morph Ball tunnel opposite the Temple Access door. Blast open the Green door on the other side. You could have done this any time after getting the Super Missile but, except for one upgrade, it was a dead end until now.
Scan the control panel to activate the lift, and take it to the lower level.
This is a large round room with a ledge around the middle and a deep pool in the center. Get a scan of the floating soccerball like creatures, they are called Preed and are this game's equivalent of Puffers, though in fact they are Space Pirate drones. (Sometime around now you should reach the 60% scans milestone.) Before diving into the water, hop up the platforms to the top of the central pillar and blast open the Missile door near the ceiling. If you fall in, locate the doors into the central pillar near the bottom to be fired to the top.
Save Station B
This is the only save station in this part of Torvus, so you'll want to return here fairly often.
Hydrodynamo Station (cont.)
Jump into the water and get to the lower ledge around the central pillar. If you fall to the very bottom then switch to Morph Ball and ride a current that flows up the outer wall to get to the next level up. Scan the large swimming creatures here. They're Bloggs and they appear often down here in several forms. The only time you can hurt them is when they're swimming straight at you with their jaws open, so it takes a bit of nerve to get a shot in.
Locate the scannable pillar on one of the side ledges on the lower level; you will be getting to the two others shortly. Get around behind it and scan it to release one of the three locks attached to the central ledge. Get back to the center and use the Orb Cannon to fire yourself back to the top. As long as you're up here you might want to get a quick save in.
At some point, either by restoring from a save or by leaving the area and coming back, the original Bloggs in this room will be replaced by their immature cousins, Blogglings. Get a scan when they appear; they're smaller than Bloggs and vulnerable to attack all the time instead of just when their mouths are open.
Drop into the water again, but this time only go to the ledge surrounding the central pillar about half-way down. When you released the first lock, a partial bridge was extend allowing you to reach the Purple door at this level. Grab the Missile Expansion here, then blast open the door. If you've been keeping track of your expansions and have suddenly noticed that you have 5 more missiles than you should have, remember that the Seeker Missile gives more missiles. This is where you would get stuck if you came here before getting the Seeker Missile.
Follow the tunnel. About half-way through a sparkling ball of light zips pasts you.
As you enter, the ball of light turns into Dark Samus, who chuckles mockingly at you and disappears again.
If you check the map you can see that this is one of three rooms connected by a ring of tunnels surrounding the main station in the center. The room itself is filled with water and there are Bloggs swimming around. Jump in and defeat them to activate a Spinner at the bottom of the pool. Note that once you jump you're committed since there's no way to get back to the entrance.
The Spinner controls the position of a Morph Ball track in the floor, with positions to start left and go right (red) or start right and go left (blue). Whichever one you pick, you'll be coming back to do the other later. The one going left, through the White door, is harder and we recommend doing that one first; the reasons for this will be explained later.
So keep spinning the Spinner until the path lights up blue, then drop into the blue hole on the right and follow the path left.
Transit Tunnel West
Switch to Morph Ball and let the current push you into the Orb Cannon; this shoots you into an underwater maze. You need to drop bombs to break through a barrier and reach a Bomb Slot, and when you activate it the flow of water changes allowing you to get the rest of the way through the maze. A second cannon takes you to the end.
This is another water filled room. What you need to do is get to the White door above you and to the left so you can get back to the Hydrodynamo Station and release another lock. That's going to take a bit of doing though.
First, drop into the water and defeat the Blogg there so you can work in peace. Locate the two platforms with purple crystals underneath them. Shoot the crystals with the Dark beam to flip the platforms; with the spikey side down you can use the platforms as stepping stones. While you're down here, get a scan of the hologram on one of the walls.
Get back out of the water by hopping on the series of ledges near where you came in. Now use the stepping stones to get to the far side of the room and use the Bomb Slot. This opens a gate to a portal under the water. Jump back in and use the portal.
Crypt (Dark side)
Defeat the Dark Troopers here, then locate the Spinner on a platform above the pool. Note that, although there is less water in this version of the room, it's poisonous. Use the Spinner to move the laser to the right; this moves the corresponding laser on the Light side. There's nothing else to do here for now, so use the portal to get back.
Gathering Hall (cont.)
The laser is now pointing at a statue on the wall, which is somehow using the energy to extend a ledge over the water. Defeat the Blogg, activate the crystals and get to the Bomb Slot as before. This time hop to the new ledge on the left, and from there is the Orb Cannon and fire yourself, finally, to the ledge with the White door.
Follow the passage. There are only a couple Preeds standing (floating?) in your way,
Hydrodynamo Station (cont.)
That whole side trip through the Gathering Hall and the Dark side was to reach the platform that you're on now so you can scan the pillar there. So whatever you do, don't leave the ledge until you get the scan unless you want to do the whole thing over again. Scanning the pillar releases the second lock. Before going on to the next lock, you'll probably want to get back to the save station and save your progress.
The reason, and this is also the reason you should do the hard part first, is the game pulls a bit of a troll move on you when you release the third lock. The ledges on the central pillar move so you can no longer reach the Orb Cannon which allows you to get out of the water. That means you can't save your progress between now and defeating the next boss. And so if you do happen to lose the boss battle, you have to do at least one of side trips over. Not that the battle is especially difficult, but it you are going to have to redo a side trip it might as well be just one, and the easier one at that.
Training Access (cont.)
Now it's time to do the other side trip, so get to Training Access as before. This time you'll meet some creatures crawling along the ceiling, so get a scan of them before you clear them out.
Training Chamber (cont.)
The Bloggs have been replaced by Blogglings, but you'll still want to defeat them so you can use the Spinner in peace. This time create the path going right (red) and use it to get to the Black door. Get a scan of the hologram here before you leave though.
Transit Tunnel East
Hop into the Orb Cannon as in this room's wertern counterpart. This time you only have to navigate some pipes to get through.
Defeat the Bloggs, then locate the ramp of rubble nearest the Grey door to get out of the water and follow the ledge to the Black door. Get a scan of the dead Luminoth in this room before you exit.
Follow the passage. There are only a few Brisgees in your way.
Hydrodynamo Station (cont.)
The second side trip is now done, so scan the pillar to release the final lock. This raises the lowest ledge around the central pillar so you can get underneath. As mentioned above, it also makes the Orb Cannon inaccessible so you can't reach the save point now. Drop to the bottom of the pool and go through the door under the ledge.
There is a long stairway spiraling down; note that each step is too high for you to get back up. There is a kind of cage on the left where you can get a scan of the next boss, and you might as well get the scan now. There are Hydlings here, so shoot them to restore supplies if you need to.
Drop into the main tank and look for the exit at the bottom.
Grab the Gravity Boost upgrade. There's no boss battle here; that comes soon though. While you're here you might as well try out your new capabilities. If you remember the Gravity Suit from Metroid Prime, you'll find that the Gravity Boost does everything that did, meaning that it allows you to move in water as easily as in air and increases you ability to see while underwater. Unlike the Gravity Suit though, if you do double jump followed by a third jump in mid-water you get a jet assisted boost upward. This allows you to reach heights underwater which would be impossible in the air. Go back.
Main Hydrochamber (cont.)
As you enter the main part of the room, the door you came through closes behind you and a door opens at the top of the tank letting in the Alpha Blogg from the room above.
After the monster has been defeated, the doors open and water fans in the walls stop turning so you can boost up to their niches. From there you can boost to ledges higher up and then to the door at the top to make your escape.
Hydrodynamo Shaft (cont.)
Boost up to a ledge near the top of the room to find a portal and go through.
Undertemple Access (Dark side)
Grab the key here and go back through the portal. Continue on to Hydrodynamo Station where you can practice with the Gravity Boost to get to the surface.
Expansions (Torvus Bog)
As mentioned above, the only place the Gravity Boost helps you is in Torvus Bog, but there are still a few expansions you can get now. We'll cover most of them on the next page since they're on the way to the next upgrade, but there's an additional one in an area we've explored already.
Head back to Torvus Lagoon. (Now that you have the Gravity Boost you can finally escape from the pool in the Hydrodynamo Station. Go to the ledge near the entrance to Temple Transport Access. Drop into the water near the dead Luminoth and you should see a passage leading under the ledge. Use the Gravity Boost to reach the Missile Expansion on the ledge at the end.