The following is an in-depth guide for the eighth area of Metroid II: Return of Samus.
Go down to the bottom of the shaft and go left. Go to the left and then go to the bottom of the next shaft. Go all the way to the left until you have the option to go up. Go all the way up to the top of this area and then go to the right as far as you can go, go upwards, go left, go upwards and then go all the way to the left until you find an Alpha Metroid. Kill the Alpha Metroid, then go left out. Go down and then right Keep going right slightly downward and then go right until you can't anymore. Go upwards, left, upwards and then all the way left until you find the Omega Metroid. It takes 30 missiles to kill an omega Metroid. I recommend being at least half health when you're going to fight them, in terms of strategy it's best to stay on the move and try not to get hit. Once he's done, go to the left until you can't, go down, and then go to the right until you have the option to go down. Go down and then go left and then go down. Once you're at the bottom go all the way to the left, go all the way up, go left and then go all the way up again. Then go left and go all the way to the top of the shaft. Then go right and then go all the way up. Then go all the way to the left to fight another Omega Metroid. Go all the way back to the right until you can't, go down a bit until you see a right path. Go all the way right until you reach a shaft, then go down a bit and go right. Then go down a bit and go right through the first path you see. At the very end of of this right hallway there's an Omega Metroid. When you're fighting all of these Omega Metroids, make sure to save and heal up by killing enemies in the shafts whenever you can. Go all the way to the left back to the shaft, go down the shaft a bit and go all the way to the left again to find another Omega Metroid. Go all the way to the right to find another shaft, go all the way up and go left out to another shaft. Go up a bit and then go through the left path. Go left a bit and you'll find a hole in the floor, drop through this floor and drop to the very bottom until you have an option to go right, go right to enter the final area, Phase 9.