Metal Gear Solid 3: Snake Eater/Chyornaya Peschera Caves and Ponizovje Swamp

Chyornaya Peschera Cave Branch
In the caves, it's dark, and you've no light. Equip the cigar, and it'll provide you with a little light, but at the expense of some of your health. Head up the east path, then the left fork. You'll come to a waterfall. Look in the small alcove to the right for some ammo and a Torch. Equip the Torch as your weapon, and you can put away the cigar. Head up the thin path to the west, and north. Crawl through the small tunnel. Look to the south of the clearing for some medicine, and then crawl through the next tunnel to the east. When you emerge, look to the south for the night-vision goggles. You can now use either these or the torch to help you see, but remember that the night-vision goggles use battery power. Jump into the hole, dive, and swim through the underwater tunnel. On the other side, swim south and east to return to the starting area. This time, go up the middle fork (the tunnel). Head north into the next area.
 * Objective: Escape the Chyornaya Peschera caves

Chyornaya Peschera Cave
Right in front of you is a fork. First, go right to get the M37 shotgun. Go north through the tunnels, and you'll emerge in the left fork. Go south towards the entrance to find the Snow camouflage, then north, where you'll be greeted by the source of the hornets that attacked you earlier: The Pain.

The Pain's attacks involve commanding his hornets to attack you, throwing projectiles at you, shooting at you with his tommy gun, and having his hornets carry a grenade and drop it on you. He generally announces his attack before doing it, giving you ample time to get underwater to dodge. In general, the battle consists of going underwater to avoid The Pain's attacks, then coming up and getting in a hit of your own. Remember that you can't hurt him when he's covered with hornets, and you can't use the high-power M37 in the water - you'll need to come up onto the rock in the middle to shoot it. When his health is down to about half, he'll introduce his "Bullet Bees" to the battle, which fly at you with high speed and lodge themselves in your body, like a bullet. They also leave a distinctive pink trail behind as they fly, so they should be easy to spot. If you get hit by one, remove it with the knife, disinfect it, and apply styptic. Continue the battle as before until The Pain dies. Leave to the north.
 * Objective: Defeat The Pain

Chyornaya Peschera Cave Entrance
Head north through the cave. In the middle area, look in the alcove to the left for ammo and two Claymores. Continue north, and head down the thin winding path to the exit.

Ponizovje South
As soon as you emerge from the cave, duck down and get your best camouflage on, and take out your weapon of choice. Look into the sky for the hovering soldiers you saw fly over earlier, and take out any that come too close with a headshot. Don't move about too much until the sky immediately above is clear. When it's safe to go, head north and west at the fork.
 * Objective: Locate and infiltrate Ponizovje Warehouse

Ponizovje West
In Ponizovje West, move slowly west, and take out the soldier that comes into view. Keep going west until you have a clear view of the soldier to the north, and the building he's stationed at. Shoot the barrel to the right of the soldier, and it will explode and kill the soldier instantly. Look inside the building he was guarding for ammo and the SVD sniper rifle, and equip it straight away. Return to Ponizovje South. This time, head north.

Ponizovje Warehouse: Exterior
After the cutscene, you're presented with an opportunity to kill The End, one of the Cobras, before the actual battle with him. If you want to do so, get out the SVD as soon as the cutscene ends, take aim at his head, and keep shooting at him until he dies. If he explodes, he's dead. Move quickly to avoid his wheelchair, which will come flying at you if he dies. If, however, you want to test your skills in a battle of attrition with The End later on, let him live for a few more hours. Either way, take out the soldiers in front of the warehouse, swim over to it, and head in. Don't draw too much attention, however - the reinforcements here are equipped with shields, which will cause a lot of pain if you get hit with one.

Ponizovje Warehouse
From the entrance, look down to the ground floor, and eliminate the soldier quickly and quietly. Go down to the ground floor, and look north to the staircase, where another soldier should be on patrol. Take him down. Look in the southwest for the Thermal Goggles. Go north and up the stairs. On the first floor is a larder. Take the food inside, making room if you need to - rations and ramen last much longer than fruit and meat. Continue up the stairs, and leave.