The Last Guardian

FAQ written by burqawitz
Formatting, Chapters, Typofixes and Lecturing by selmiak

Chapter 3
   The Underground Lake  

Eventually the cave turns left and leads to a large cliff overlooking an underground lake down below. It's a long way down, but it's perfectly safe to jump down into the water below. Trico is not happy about this. He wants to follow you, but even if you call him he's unwilling to jump down into the water.

There's a small balcony coming out of the water on the left. Swim to the balcony and climb out using the stairs that lead down into the water. There's a wood barrier here. While you can't get Trico to come down into the water, you can use the mirror to have him blast the barrier with lightning from up on the cliff face. Head inside the now opened door.

Inside, there's a chain hanging down in the middle of the room. Jump toward the chain and you will grab onto it. Press to climb up the chain. Climb all the way to the top and you'll climb up on top of the structure. You can then walk out along the wood like a balance beam, and drop down with to the raised platform area. There's a box up here containing three barrels for Trico -  Barrel 7,  Barrel 8, and Barrel 9 .
Grab the box on the side closest to the wall with , then press to push it off the cliff to the area below. The box will smash open, giving you access to the barrels. You're not so high up that it's dangerous to jump down from this height. Jump down to where the barrels are.

From here, you can see Trico looking into the doorway, obviously quite interested in the barrels. Grab a barrel and throw it into the water. The lure of food will give Trico the extra incentive he needs to jump down into the water. The resulting wave will likely knock you off your feet. Feed Trico the other two barrels. You can play catch with them, but don't try to throw them over the railing. They'll hit the rail and just land in the water. Trico will still eat them, of course, but he will only be able to catch them if you lure him to the stairs without the railing, then throw them out over the stairs to him, or throw them through the broken spot in the railing.

Trico is in kind of a hurry to leave it seems - but there's another barrel in this area. This is infuriating to get, because of a poorly designed AI routine. You need Trico to sit near the waterfall for a couple of minutes - but every time you climb on him he will make a beeline for the exit to the area.
You have to call Trico over to the area with the waterfall. Trico has a tendency to not be willing to get close enough to the wall in the first place. It's very difficult to get him into position. When he arrives, you have to run up and climb up him and hurry and jump to the ivy high up on the wall before Trico turns around and leaves. Unfortunately, he has a tendency to turn his head just as you try to jump, making you cling to his head instead, and ruining your jump, and you'll have to hop down and start the process over again.
If you can get him close enough, you can reach the ivy from his back without having to climb clear up to his head - which makes it easier. But he doesn't cooperate very well.

When you finally reach the ivy, climb along it and it will lead you to a cave behind the waterfall. Inside, you'll find  Barrel 10, half-buried in the dirt. You can pull it out of the ground to feed to Trico. After as much hassle as he probably gave you to get here, you may not feel like rewarding him... but if you don't feed him the barrel then you wasted all that time anyways.

Trico will find the way out of this area for you, jumping up to a high cliff in an area you couldn't reach. All you need to do is climb on his back and wait. If he leaves without you, call him back with , then climb on his back and he will return back onto the cliff with you in tow.

At the end of the cave there's a small hole with light shining through at the end. You can jump and climb up the cliff with . You don't need Trico's help to reach the hole. Simply move toward the hole to climb through and trigger a cutscene.