The nine keys can only be found in Dark Aether. Also, these keys are protected by invisible creatures only visible with the Dark Visor. These creatures are not difficult to kill (finding them is the only hard part). Just hit them once while in Dark Visor mode, then switch back to combat mode, kill them, and get the key. You must have the Light Suit to get some of these, as they require going into areas that your Dark Suit cannot handle. There are three Sky Temple Keys in the Dark Temple Grounds, two in Dark Agon Wastes, two in Dark Torvus Bog, and two in Dark Sky Temple:
Dark Agon Wastes
Dark Oasis: You can get here via the portal from the Space Pirate's base (or any portal in Agon). Once you are in this room, Power Bomb the Denzium wall in the center. Do not go into the area without the Light Suit --the Ingstorm will rip you apart. Go underwater and switch to your Dark Visor. Kill it and take the key.
Battleground: This is where you got the second Agon key. Look in the air and there should be some platforms to jump on, only visible with the Dark Visor. The Ing creature with the key at the top. Kill it and get the key.
Dark Torvus Bog
Poisoned Bog: This room is in the upper area of Torvus, two rooms away from the Venomous Pond. Go underwater and kill the creature.
Dungeon: This room is in the lower area of Torvus. You can reach it by going through the portal in the Catacombs. There will be two Dark Grenchlers here. Take care of them if desired, then dive underwater. Get past the robots by shooting the Light Portal above their heads. The Ing and key should be at the end.
Dark Sanctuary Fortress
Hive Dynamo Works: Go back to where you defeated the Spider Guardian in the Light World (Dynamo Works). Blast open the yellow hatch door with a Power Bomb. That should lead you to a portal into the Dark World. You must traverse the chasm (either through Spiderball Boosting or Screw Attack). The Ing is on the other side of the chasm.
Hive Entrance: Go to the Dark World portal in the Hall Of Combat Mastery. You will emerge into the Culling Chamber. Proceed through the door leading to the Unseen Way. Cross the chasm of the room. You will be in another room called the Hive Reactor. Go through the yellow hatch door at the bottom to reach Hive Reactor Access and Entrance Defense Hall. Go through the door again and you will be at the Hive Entrance, a Dark version of the Sanctuary Fortress' entrance. Screw Attack all the way over to the other side and ride the Light Portal up. Then, Screw Attack again over to the other side, the top level above the entrance where you came from. The Ing and the key are there.
Dark Temple Grounds
Ing Reliquary: Go to the Sacred Path in the Light World and take the portal there into the Dark World. You will emerge at the Profane Path. Note: There is a beam ammo expansion here that you can get by solving a sonic puzzle with the Annihilator. The rooms along the way only have one way to go. Follow the one-way path and keep going until you reach your destination (the path is very linear). Check your map to see where the next door is located. The room is on the second floor of a large complex looking structure. Again, do not go through these areas without the Light Suit.
Accursed Lake: In the Light World, go to the Temple Assembly Site. There is a door with a purple crystal on it. Search around and shoot it with the Light Beam and activate the portal behind it. You will emerge at the Plain Of Dark Worship. Go through the Seeker Missile purple door and continue along the one-way path. You will now be at the Accursed Lake. The Ing is floating in the air. Kill it and get the key.
Defiled Shrine: This final key is actually very close to the Sky Temple Gateway (your destination after you get the nine keys). In the Light World, start at The Hall Of Eyes. Go through the portal here. You will emerge in Base Access in the Dark World. Go through the green hatch door. At the War Ritual Grounds, go through the only door there. You will be at the Shrine Access. Go through the Morphball tunnel and when you emerge, go through the green hatch door. The Ing and the key are in here.
After getting all nine keys, do whatever desired to prepare for the final fight. When you are ready, go to the Sky Temple Gateway in the Dark Temple Grounds. Get all the Energy Tanks, Power Bombs, Missiles, and Missile Combos if desired.
