The world of Final Fantasy 15 is as big as it is fascinating, and there's a huge amount of exploring to be done to see all it has to offer. Along the way, a number of questions will be raised about how to access certain items and areas, which we will be answering below along with walkthrough videos to show exactly what you need to do to unlock them.
How to get the airship, and reach the secret dungeon
Airships have long been a feature of Final Fantasy games, and Final Fantasy 15 is no exception - though the route to getting one here is a little different. First, you'll need to complete the game, then use your clear data to travel back in time to Lucis. Here, you'll find a load of new side quests have unlocked, and the one you're interested in is Formouth Garrison at the Imperial Base.
This is a difficult battle with a tough boss appearing after waves of enemies, but once you finish it you'll earn the 'Strange Engine' item. Now, visit Cindy at the garage and use this item, along with the two items you unlocked at the end of chapters 5 and 6, to upgrade your vehicle to the Regalia Type-F, which not only flies but also has unlimited fuel.
As well as giving you the ability to fly around all over the map, the Regalia Type-F also lets you reach the secret dungeon to the west of the map near the volcano. Look for the orange line north of the loop on your map, as this is the 'landing strip' you need to aim for. Once safely back on the ground, head northeast to find the hidden area, which is only open at night. Inside is a massive, hours long chamber full of challenges and puzzles - continue reading below for details on how to complete it.
How to complete the Pitioss Ruins Dungeon
Once you've unlocked the Regalia Type-F, you can now follow these steps to access the secret Pitioss Ruins Dungeon. First, go to Lestallum and head to the easternmost alley at night between 21:00-05:00. Interact with a window to start a special quest, then travel to the outpost at Ravatogh Volcano and talk to the chef to add a marker to your map. Fly the Regalia Type-F to the 'landing strip' to the north as described above, then head to the marker to complete the quest.
Now, wait until night time and you can activate the elevator to descend into the Pitioss Ruins, full of trials and puzzles to challenge you. You can't die here as any mistakes will simply return you to the previous checkpoint, and although it could take you several hours to find your way through unaided, our complete video walkthrough will ensure you don't get completely stuck along the way.
As well as a ton of great items to be found along the way, your reward for completion is an item called the 'Black Hood' - only Noctis can equip this, and when worn it will allow him to automatically dodge incoming attacks. Once you've beaten the dungeon, make sure you save before trying to leave in the Regalia Type-F, just in case you have problems during takeoff and end up crashing into oblivion.
How to unlock the eight vault doors
Hidden away in Final Fantasy 15's dungeons are eight huge doors, and these are the steps you need to take to unlock them. First, you'll need to have completed the game and returned to the past version of Lucis, then make sure you clear these four optional dungeons - Crestholm Channels, Balouve Mines, Castlemark Tower, and Daurel Caverns.
Once done, go and speak to Ezma at Hunter HQ to the north of the map, and she will hand you a key that you can use to unlock all of those hidden doors. Your quest log will fill up with new trials inside many of the dungeons, pitting you against high level enemies while disabling your minimap to try and confuse your navigation.
Handily you'll find a camping spot after a few levels which will let you restore your health and auto-save your game - something that doesn't normally happen inside a dungeon. Keep exploring the caverns and you'll find some of the best weapons and rarest items in the game, and once you've finished them all you can return to Ezma to claim the Huntress medal. This can either be sold for 50,000 gil or used to craft a Limit Break spell, an ultimate magic attack which can break the 9,999 HP damage barrier most other attacks brush up against.