Final Fantasy X/Secrets and Sidequests/Baaj Temple
 Return to Baaj
To find Baaj Temple, on the airship search just below Besaid island on the map (X co-ordinate 11-16, Y co-ordinate 57-63). When you arrive there, you will recognise it as the place where you were first dumped in Spira, however only a small portion will now be available to you. Save at the sphere when you arrive, and jump off the end of the platform to be re-united with an old friend.
With 32 767HP and very high defences Geosgaeno is just as tough as he looks, and this time round you're actually going to have to defeat this tough fiend. As this battle takes place underwater, you will only have Tidus, Wakka and Rikku at your disposal, and coming into the battle with as many members as possible in overdrive will always help. Geosgaeno doesn't have too many different attacks, but most notable is Stone Punch which will petrify and shatter one character, and failing that will simply deal damage to them. Clearly this is a devastating blow, and its effect can be reduced by armour with Stoneward/Stoneproof (although not strictly necessary). Geosgaeno will also attack with KO Punch, however this doesn't permanently remove your character from the battle. As well as powerful physical attacks, Geosgaeno will sometimes swallow and then spit out one of your characters for major damage, as well as absorbing their positive status effects. Don't defeat Geosgaeno with one of your characters inside him unless you want to see the game over screen.
Your first move should be to cast Hastega, and then unleash any overdrives you happen to have (if you've already captured enough monsters, you can mix a Shining Gem and a Supreme Gem to knock off 20000HP). Your attacks will probably only be doing about 500HP a hit, but coupled with quick hit (if you have it) this damage can build up quickly. Geosgaeno is weak against all the elements, so exploit this by using Element Reels if you don't have Attack Reels, and any Fire Gems (stolen from flame flans) or equivalent items you have. Fire Gems will quickly deplete Geosgaeno's health, so if you're having trouble go to the Calm Lands and start stealing them from the flans.
 The Dark Aeon
Before entering the temple if you have the Celestial Mirror, search around opposite the temple entrance about halfway down for a chest containing Lulu's Onion Knight. Otherwise head towards the green square on the map, and enter the temple through the submerged door. Head up the steps inside, and enter through the next door to find 6 statues and a large seal in front of the Chamber of the Fayth. Before examining the statues, turn around to find 2 treasure chests in the back corners which both contain very useful items.
If you examine the seal, you will learn that each of the statues corresponds to a destruction seal in each Cloister of Trials you have been through, which is broken by opening the treasure chest that you found with the destruction sphere. Examine the statues, and find that they don't all light up. Out of the 6 Cloisters of Trials:
- Besaid's seal is covered in the walkthrough, so if you need to go back and break it return to Besaid using the guide as a reference (if you then enter the fayth you will find a chest containing a Hi-Potion, White Magic Sphere, 2 Potions, Elixir and an Evasion Sphere). In the International version you will find Dark Valefor blocking the entrance to Besaid, so see the Dark Aeons guide for help with this.
- Kilika's seal can be broken by following the same method as for Besaid's, except the chest in the Chamber of the Fayth contains a Defense Sphere, Accuracy Sphere, Luck Sphere, and an Agility Sphere.
- Djose's seal can be broken again with the same method, except the chest contains an Agility Sphere, Magic Defense Sphere and a Luck Sphere.
- Macalania's Seal can be broken with the same method, except the chest contains a Magic Defense Sphere, Accuracy Sphere and a Magic Sphere. In the International version you will find Dark Shiva blocking the entrance to Macalania Temple, so see the Dark Aeons guide for help with this.
- Bevelle's seal must be broken to leave there, so you need not worry about returning to this now inaccessible place.
- Zanarkand's seal can only be broken by a second visit to the trials, which is covered below.
Now find out which statues light up (you can tell which one they are because for example Djose's will have a small crackle of lightning), and go back and break the remaining seals. Note that the hidden fayths have no trials, although you will still find a strength sphere in Yojimbo's Chamber of the Fayth, and a Defense Sphere in the Chamber of the Fayth at Remiem Temple.
 Zanarkand Destruction Sphere
To break this seal, first return to Zanarkand Ruins and make your way along until you reach the trials. You will notice the screen in front of you now shows 7 white 2 by 2 blocks. As with the original trials, you must find these blocks by stepping on the small lights on the floor. There are 3 of these white blocks in the first room, in the top right, mid-left and mid-centre. The final 4 are found in the second room, on the mid-left (2nd from the white-blue glyph), mid-top (2nd from the blue glyph), top-right (2nd closest to the stairs) and mid-right (across from the red/pink glyph). After lighting up the 7 squares, the screen in the first room will move away revealing the destruction sphere. Take this and place it in the hole on the right of the screen in the second room to reveal the chest, which can be opened to break the (hopefully) final seal.
When you have broken all the seals, return to Baaj Temple and examine all 6 statues which should all now light up. When they do, the large seal will break, and you will be able to enter the Chamber of the Fayth to talk to the fayth and then obtain the Dark Aeon, Anima.
To return to Cid's airship, retrace your route until you get near the center of the flooded arena, and when the dialogue box saying surface/dive appears choose surface (even though you are already on the surface of the water) and it will transport you back onto that broken bridge way over your head and from there you can just walk back to a save sphere for your pickup.