Aht Urhgan Mission 9: Undersea Scouting

Walkthrough

Watch the cutscene for an explanation of the ruins.

Bhaflau Thickets Map 1 (see wiki)

Travel (F-6) in Bhaflau Thickets and speak to NPC Kamih Mapokhalam.
She tells you that in order to enter the Alzadaal Undersea Ruins zone you must trade trade her an Imperial Silver Piece.
She also says that if you trade her three Imperial Mythril Pieces she will give you a map of the Alzadaal Undersea Ruins. Trade her these first for the map.

Alzadaal Undersea Ruins Map 7 (see wiki)

Approach the Gilded Doors (H-. Mission Ten is started as soon as the cutscene begins.
NOTE: There are no monsters in this section of Alzadaal Undersea Ruins.

If you already have access to the ruins via another runic portal (such as Nyzul Isle), the cutscene will begin as soon as you walk off the teleport pad upon warping into this area (Map 7). There is no need to touch the doors in this case.

If you still do not get the cutscene, try using Escape if you have it, or just zone into Wajaom Woodlands or Bhaflau Thickets, and then back in Alzadaal Undersea Ruins. Walk towards the Gilded Doors and you should get the cutscene.