There are stairs leading down to the waterway in Lowtown, but they are normally barred to keep unwelcome visitors down in the sewers where they belong.”
Travel back to Rabanastre and once you have obtained the Sunstone in the Giza Plains. Return to Old Dalan in Lowtown to move on to the next part of the story. Remember not to open the treasure chest outside Dalan’s Place if you want to obtain the Zodiac Spear later on (and remember that this note about obtaining the Zodiac Spear does not apply if you are playing The Zodiac Age PlayStation 4 version of the game.
There is a short cutscene just outside of Old Dalan’s House where Penelo gives a heartfelt speech to Vaan and leaves the party. Vaan is on his own once again.
Enter the house and speak to Old Dalan. Dalan will give Vaan the Crescent Stone and will direct him to go to Storehouse Five to gain entry into the Palace. The Crescent Stone will allow Vaan to gain access to the treasury once he gets far enough inside. There is a short cutscene that takes place involving Vossler and the Remnants of the Order before the game returns to Vaan in Lowtown.
Use the map and screenshot below to help you find Storehouse Five which can be found in the Northern Sprawl of Lowtown. Take a left (heading north) when you exit Old Dalan’s House.
Kytes will initiate a conversation with Vaan as soon as he attempts to enter the Storehouse. He will help Vaan gain entry to the locked door on the left that Old Dalan spoke of and will give him a few items to see him off on his journey – 2 Potions and 4 Phials of Eye Drops. Enter the Garamsythe Waterway doorway on the left to continue.
Enemies: Dire Rat, Steeling, Ichthon
Central Spur Stairs
There is a Save Crystal immediately to the left of the entrance to the Garamsythe Waterway. Use it to save your game before proceeding. Head west, past the Save Crystal, and up the stairs into the next area. The passageway leading east away from the Save Crystal leads to a dead end though it may have a treasure chest at the end of it if you do feel like exploring.
The pathway through the Garamsythe Waterway is extremely linear – there are very few ways for you to get lost. In the first area, make your way northwest, crossing the bridge and into the next area. Use the maps below to assist you.
North Spur Sluiceway
Once again, continue along the linear pathway, but this time to the west. There are a few areas on the south side of the map where treasure chests are likely to spawn. These treasure chests have a fairly good chance of containing some good items (an Oak Staff and a Mage Masher to be specific) though they may not have randomly spawned and they may not contain those specific items depending on how lucky you are. Don’t fret if you do not get them during your play through as they are not that important.
Continue along the pathway using the map below to assist you until you reach the northwest section of the zone with the stairs leading up to the next level.
Approach the stairs and Vaan will mention that the Palace should be right at the top.
Choose to “Climb the stairs” to continue with the story.