Sky Temple Key

In Metroid Prime 2: Echoes, the Sky Temple Keys were ten keys that locked the Ing's home on Dark Aether. Similar in appearance to the Dark Temple Keys, these artifacts were hidden on various parts of Dark Aether by Ing Flying Caches. They resemble floating gyroscopes with white jewels at their centers. Collecting all of them is vital to open the way up to the Sky Temple, where the final boss of the game patiently awaits Samus.

Locations
Samus only has to collect nine out of ten Keys (as one of the Luminoth Keybearers, A-Kul, managed to retrieve and place back one of them to the Sky Temple Gateway), and to do so, she can scan the bodies of the lifeless Keybearers to find that the Ing carried them to the Dark Aether equivalent of the places where said Keybeares died. This means that Samus, after finding one corpse, has to find the closest Dark Portal, enter it and then make her way to the Dark variation of the corpse's recorded location; once there, she has to use her Dark Visor to locate a Flying Ing Cache, whose defeat will release one of the Keys; this procedure is repeated until all Keys are found.

A second source of clues come from the Sky Temple Gateway, where A-Kul foresaw the locations of the fallen Keybearers and led messages regarding where to find the Keys they retrieved. The key hunt can begin relatively early (after the player finds the Dark Visor), but can only be completed after gaining the Light Suit, as some Keys are hidden either behind Light warp spots or under poisonous water. The Keys are located in the following zones:


 * Battleground, Dark Agon. Keybearer found in Mining Station, Agon Wastes. Notes: Use either Screw Attack to move at once to the Ing Cache's location or the Dark Visor to go there more safely through invisible moving platforms.
 * Dark Oasis, Dark Agon. Keybearer found in Reactor, Agon Wastes. Notes: One Power Bomb is required to expose the toxic pool, and the Light Suit is to swim through it.
 * Poisoned Bog, Dark Torvus. Keybearer found in Lagoon, Torvus Bog. Notes: Light Suit is required to swin through toxic water.
 * Dungeon, Dark Torvus. Keybearer found in Catacombs, Torvus Bog. Notes: Same as above, and don't forget to scan the Watchdrone.
 * Hive Entrance, Ing Hive. Keybearer found in Entrance, Sanctuary Fortress. Notes: Use Screw Attack to catch the Light warp spot, the Light Suit to use it and SA once more to reach the Cache's spot.
 * Hive Dynamo Works, Ing Hive. Keybearer found in Powerworks, Sanctuary Fortress. Notes: Return to where the Spider Guardian was defeated (this in Light Aether), there is a door asking for a Power Bomb to be opened that leads to a Dark portal, which shows the Cache's hideout.
 * Accursed Lake, Sky Temple Grounds. Keybearer found in Industrial Site, Temple Grounds. Notes: Seeker Missiles are required to open the door that leads to the lake.
 * Ing Reliquary, Sky Temple Grounds. Keybearer found in Cavern, Temple Grounds. Notes: The Dark Portal that leads you to this area is by no means close, it's on the Sacred Path area; also, Light Suit is required due to the presence of Ingstorm.
 * Defiled Shrine, Sky Temple Grounds. Keybearer found in Impact Site, Temple Grounds. Notes: Collect this one last, since it's close to the Sky Temple Gateway and, by that moment, having already the other eight Keys helps you to complete the hunt at once.

Trivia

 * If Samus uses her Dark Visor while being where a deceased Keybearer is, the silhouette of the Ing Cache holding the snatched Key can be seen, but cannot be killed from Light Aether.
 * Coincidentially, the ninth Key (see the above list) is located in the Dark Aether variation of where samus landed to the planet.
 * Keys one, six, seven and nine can be collected prior of the collection of the Light Suit, so the player can shorten the period of the quest by getting them before the call of their requeriment.
 * Some players have criticized the search of the Keys due to the difficulty of finding the hints to find them and the high backtracking (to every region) involved.