Completing Area 1

Walkthrough: After exiting the room the same way your entered, cling to the wall to the right of the Save Station. If you roll up, you'll find the next Missile Expansion. Keep scaling up to reach the next door. After entering, you'll find one of the Metroids. This one will be one of the Alpha Metroids. After defeating it, explore the massive room with many treasures inside. If you start by climbing up the same wall to the ceiling, you will eventually find one of the Energy and Missile Charge Stations (you'll have to Bomb to reach them). To the left of the Missile Station is a breakable wall that leads to another Missile Expansion.

From that Missile Expansion, drop off to the left and Bomb the block in the corner. Two doors will be revealed, but you won't be able to access either of them. So start heading back to the area where the door to the lava section was. On the way there, you can find an Aeion Tank that you can reach with the Spider Ball. Drop down past the lava door until you see the door at the bottom. Enter the passageway above it to find yet another Save Station. Break the walls to get across and reveal the next Missile Expansion, the same that can be accessed by this side.

Avoid the red flora in the next room to prevent taking damage as you enter the room on the right. It is here you'll find the next Metroid. Again, it's one of the Alpha Metroids. After defeating it, return to the previous room with the poisonous flowers. Bomb the wall on the left and head inside. Make it to the bottom, and then there will be a door to the right. There will be one of the Alpha Metroids here as well. Defeat it and start heading to the area on the left. You'll have to Freeze your enemies popping up from the ground with your Ice Beam; Charge for them to be frozen in place longer. One the final frozen foe, missile to break the ceiling and reveal the next room. Here is where you'll find another of the Alpha Metroids, the final Metroid of Area 1.

From here, return to the Chozo Seal at the beginning of Area 1 and stand on the platform to lower the lava. Drop down and you'll come to an area with a tight passageway. You have to use your Spider Ball above the area you'd actually like to go through, since the blocks will easily crumble and resurface if you shoot them. After making it through, there will be another puzzle to solve. There will be a vent that prevents you from destroying blocks, forcing you to use the passageway above Samus. Just up to the passageway to avoid the missile block, hanging on the end as you do. From there, jump to the edge of the left side, giving you the perfect path to the missile block. Destroy it, and proceed. To the left will be the elevator to Area 2.

Missile Expansion 1: In the big and open room, Spider Ball until you reach the ceiling. To the left of the Missile Recharge Station, Bomb the wall and ensuing enemies. There will be another wall below the Expansion, but vents will prevent Bombing it. Destroy the two blocks under the vent first, then stand and shoot a missile to the weak spot on the wall to obtain the upgrade.

Missile Expansion 2: Get to the highest point of the big room. Go underneath the long platform on the left, then Bomb the center to reveal the Missile Expansion found underground.

Missile Expansion 3: This one is blocked by the Bomb Wall, as well as a vent, on your way to the flora room. Ignore the wall as a whole, passing it to the right. In the very next room, simply Bomb the center of the left wall to get to the Expansion.

Energy Tank: After defeating the first Metroid within the door to the right of the big area, Spider Ball up the wall to the right. At the top, Bomb the corner to find the passage way to the tank.

Aeion Tank: Return the room with the yellow substance splattered throughout. Jump out of the water and Spider Ball to reach the ceiling. Bomb the weak spot to reach the tank.