The second disc continues from the Forgotten Capital. Head forward, and you see Cloud's weird mind projection of Sephiroth heading to the right path.
The next screen should be fairly straightforward, head up the conch-like structure. The chest, if you're able to reach it through the ground, contains a Viper Halberd. The screen after that should likewise be fairly simple; you can climb up and down the vertical shafts. The chests contain Bolt Armlet, HypnoCrown and a Megalixir. On the bottom of the very long ladder, you'll find a Magic Plus materia. Head up that ladder, and out through the next cave that has a chest containing a Power Source.
Now you're back on the world map. Head northwest until you find a city.
Icicle Inn
This place seems to be the northernmost point of civilization. To get further north, you need two items. Talk to the folks in the big house, and you'll find out how to get the Glacier Map - it's actually hanging on the wall, and you can just grab it, though the owner thinks you're a bit bold for taking it before getting his permission. Then, as you find out, there's no way to get further anyway. As you investigate things, you'll find out that the kid in one of the houses has broken his leg and will let you take his snowboard. Stock up on items if you want and check the northwest house for a few videos talking about Ilfana, Aeris' mother.
Then Elena and some Shinra soldiers show up. This is a little bit of a comedic cutscene: Use the controller/keyboard as indicated, move left out of the way to dodge. Either Elena manages to punch you in the nose, or she misses by a mile and goes down the hill.
Great Glacier
Next you should snowboard down the hill. Talk to the man to find out how to snowboard, and for more details look on the Snowboarding page. Then just head down the hill. It doesn't really matter what route you take, you just end up at a different part of the glacier.
Now, it's time to navigate around the glacier. Press 
to check the map. Your objective is to identify where you are, so look for landmarks in your current location that looks a bit like the ones in the map. When you've located your position, head toward the red checkmark on the map. Refer to the Great Glacier page for further details.
You will either reach the foot of the mountains on your own, or you'll wake up there if you slump down and freeze to near death. If you freeze, then the climber guy finds you and nurses you back to health.
From the climber guy's house, if you head south you'll reach a large snow field where you have to place markers to keep following a straight path through the snow. If you head directly south, there will be a cave with an All materia inside. Head all the way south by following your markers in a straight line, until you reach a new area with some hot springs. Go to the bottom left to touch it, then head back to the field and go directly east to reach a cave where a snow lady lives. If you touched the hot springs, you'll be able to fight her and win the Alexander summon materia. Head back north or get lost again to go back to the basecamp.
Climb the cliff
The climber will explain how to climb the cliffs and how to keep your body temperature up. You can take various paths that lead up and away. The first cave you enter has a Ribbon, among other items. Since this is the only time you'll be on the cliff, you should grab it since they are very useful and very rare. Enter the cave and go up through the door. Then, go left and down through the next door. Go down and right across the ice bridge. If you keep running into the correct spot in the wall on the right, you'll run through it, into a room with a box with the Ribbon.
There's not much to the caves, although they do have some monsters in them like the Stilvas, who teaches you interesting Enemy Skills, like Trine and especially Magic Breath, which is a very useful skill. On the cliff proper, you'll run into Malboros, which teach the Bad Breath Enemy Skill. Equip either a White Cape or a Ribbon, because this Enemy Skill has many status effects. In the first cave, the idea is to find your way to a big rock, then push it down, and follow it. In the second cave you'll find a save point; the idea is to get to the balcony above the room and knock down the huge icicles, which can be done in a single turn by casting Fire3 at them.
In the third cave you'll find a black-robed guy that seems to be dying. Then a big monster shows up.
This is a nasty two-part boss - they're identified in targeting as "Schizo (left)" and "Schizo (right)". The left side does Fire, the right side does Ice - that is, their attacks are based on those elements and they absorb that damage type. Typeless summons, like Odin or Bahamut, are good. Things like Magic Breath and Kjata are utterly useless and just heal the thing. The worst part is that once you kill either head they explode with lightning ball, so watch out for that too. Dragon Armlets (from the dragon in the temple, or the Blue Dragons in the preceding few rooms) are handy though, as they soak up the damage a bit. Big Guard is priceless here. Magic Hammer enemy skill is very strong against this boss because all of its attacks are magic-based.
| Level | Hit Points | Magic | Weak against | Strong against | Absorbs |
|---|---|---|---|---|---|
| 43 | 18000 | 350 | None | Gravity | Fire, Cold |
After this boss fight, which turns out to be the hardest one in this section, it's time to head out and to the top of the cliff. A nice view over the Northern Crater.
Sephiroth
Go down the cliff. If Tifa isn't in your party, she shows up and insists on going with you. In the first room, there's a Neo Bahamut materia. Here you'll see the Shinra approaching from the skies. There are two screens where you need to cross the chasm. As the instructions say, time crossing the gaps when the wind is quiet, otherwise you get knocked back and you need to fight some weak enemies.
After passing a lot of black robes, you again meet up with Sephiroth, who's killing the black-robed guys.
This battle is so simple, you barely have time to set up barriers and try out a few non-elemental summons or perhaps Enemy Skills. Jenova's attacks are now fire-based, you probably have something to counter those already, like Dragon Armlets or Fire Rings. All in all, this fight is absolutely simple.
| Level | Hit Points | Magic | Weak against | Strong against | Absorbs |
|---|---|---|---|---|---|
| 55 | 25000 | 800 | None | Gravity | None |
Now, things start to make a little bit more sense. Have Cloud give the Black Materia to either Barret or Red XIII (others will refuse to take it, and you can't give it to a party member either). There's a save point here. Head up after you've saved, and watch the long cutscene that follows.