Now that you've found the Ice Beam, we'll be able to track down the Gravity Suit hidden in Phendrana. Go back to the Save Room off the Reflecting Pool and go through the small opening to find the elevator leading down to the Overworld. Ride it down. In the large winding tunnel beyond the elevator you'll encounter a few Geemers, if you hit them with a blast from the Ice Beam they'll stop moving, shoot them with a missile and they'll explode.
Go through the tunnel past the giant tree growing through the ruins to find a small tunnel with Missile TO.03 hidden among a bunch of Venom Weed. Grab the missile and go through the next door. Go outside to reach the Frigate Crash Site - a massive open area where the Space Pirate frigate crash-landed when the core exploded at the beginning of the game.
If you've been following all these directions so far this'll be your first visit to the area, but you can easily access this room via the Landing Site once you find the Morph Ball. Walk over to the edge of the cliff you're on and look down. Two Flying Pirates will come up after you, try to freeze them with the Ice Beam and fire a missile to blow them up instantly.
Below is a large lake in front of the remains of the frigate, Missile TO.04's hidden underwater but you'll need the Gravity Suit to reach it. Three critically-injured Space Pirates are sitting just below at the base of the cliff, you shouldn't have any trouble taking them down. Way over on the other side of the lake you'll find a damaged crate with a blue substance seeping out of it.
If you walk close enough to the substance the warning meter will go crazy - this stuff is pure Phazon, don't touch it. Now you've got a decision to make. Inside the crashed frigate you'll find many familiar rooms from when you were in the ship up in orbit, but the place will be a wreck, full of overgrow weeds and almost completely submerged in water.
Due to the water you won't be able to move around much, you'll eventually reach the sloping elevator shaft but you won't be able to continue on (the game will tell you). To make things more convenient, we'll be going straight to Phendrana for the Gravity Suit, then we'll come back to the frigate.
For now head over to the Magmoor Caverns East elevator. On the way save your game at Samus' gunship. Once down in Magmoor, head left and journey to the Phendrana Drifts South elevator - keep in mind that you can freeze the flamethrowers here with a blast from the Ice Beam. Up in Phendrana, turn around and climb up the Spider Ball track along the wall.
Go through the white door there to reach a new uncharted region of the Drifts, you'll also hear a funky new tune playing in the background. In this first tunnel, you'll see Energy Tank PD.03 hidden within a tunnel blocked by ice, but you'll need the Plasma Beam to melt the ice. Go down the corridor and through the door at the end to reach the tall shaft-like Frozen Pike.
Climb down the shaft, the first door you'll find leads to a tunnel connecting this area with the Research Core - the room where you found the Thermal Visor. There's no need to go there now, so keep going down the shaft. There's two more doors near the base of the shaft, the lower one's underwater so you won't be able to reach it yet, go through the higher-up door instead.
Roll through the narrow tunnel you'll find, at the end watch out for the two Ice Beetles and the Scarab swarm ahead. Go through the door to find the Frost Cave. In some versions of the game you may be greeted by an unusual sight here - a strange, thin, elongated Metroid complete with a long barbed tentacle. Scan this Hunter Metroid for your Log Book before dealing with it in the usual Ice Beam/Missile manner. There's another interesting creature flying around in here, scan it to reveal it as a Glider - these creatures are the only harmless lifeforms on this planet, so it's nice to know that you've got at least one friendly here.
You can use Gliders to swing across with the Grapple Beam, so you won't be able to do anything with it yet. Knock down the two stalactites across the room to gain access to the two purple doors. Missile PD.07 is hidden below the ice at the base of the room, but you'll need the Grapple Beam to gain access to it. The door up on the right leads to Save Station C, save your game before heading through the other door.
Beyond the other purple door is a narrow winding tunnel, roll through it and go through the next door to reach Phendrana's Edge. Two Flying Pirates will greet you here, deal with them both first. There's not much to be done yet up higher in this shaft, so drop down into the water below and go through the underwater door, just watch out for the two Jelzaps underwater and don't forget to scan one.
You'll need to hit them when they open up, a well-aimed shot with the Ice Beam will freeze it, fire again to blow it apart. Proceed through the next tunnel while watching out for the Scatter Bombus, through the next door you'll reach the Hunter Cave. Up above in this large room three stalactites loom overhead, shoot them all down (two of them will land in the water while flattening Jelzaps).
The two doors way up on the walkway ahead can't be reached, so we'll be going through the door over at the top of the cliff on the other side of the lake. Try to shoot the Flickerbats flying around below as they'll try to knock you into the water, then use the downed stalactites to reach the door. Go through the next tunnel and head through the underwater door to reach the Gravity Chamber - home of the Gravity Suit.
Go over to the open area around the corner and scan one of the Aqua Reapers failing about below. You can't destroy them, but you can still freeze them with the Ice Beam. Shoot the tentacles with the Power Beam to send them down into the ground, then quickly jump across to the cliff opening on the other side (watch out for the Jelzap).
Around the next corner is another open area with more tentacles. Go around them and head up to the cliff on the opposite side. Climb up to the small alcove at the end, then you'll find the mighty Gravity Suit waiting there for your arrival.