Dreadnought

After getting the Sunfire from Kashuan Keep and returning to Altair, you find out Hilda was captured alongside Cid. 10 missable chests inside the Dreadnought.

Boarding the Dreadnought

Head northwest from Altair. It's a long walk through the mountains. Eventually you'll reach the Dreadnought's landing site.

Save before entering. This is a one-time dungeon with missable chests and bestiary entries.

Show the guards the Pass you grabbed from Bafsk Cave to board.

Dreadnought

The Dreadnought has 5 floors, 10 chests, and no bosses. Collect everything before using the Sunfire.

1F. Go up the stairs in the top left corner for chest 1 (600 Gil). Go back down and take the stairs in the middle going down.

Go right and walk through the wall to find chest 2 (Sleep Blade); monsters guard it. Double back upstairs, then head up and right. At the junction, go right and through the door to 2F.

2F. Head down to the split. Go right; follow the path for chest 3 (Hi-Potion) and chest 4 (Potion). Back to the split, head all the way left. Bottom left corner has chest 5 (Dark Bow). Go up, then right, walk down for chest 6 (Thief's Gloves). Head right and open the green gate to find the prison cells.

Cid takes Hilda to safety via his airship. Make your way back to 1F.

3F. Back on 1F, go south to the stairs leading down. Follow the path around to the door and continue downstairs.

4F. Follow the path to the top right corner. Four chests here: Trident, Main Gauche, Ice Shield (monster chest with Hill Gigas), and Giant's Helm. Head to the middle and go up the stairs; follow the doors to 5F.

5F (Engine Room). A maze with guards patrolling. Go right and up, then left; follow the path around the room. Weave through corridors to reach the door at the top.

Destroying the Engine

Open your inventory and select the Sunfire. The engine ignites. Cid leads your party to his private airship. You escape as the Dreadnought crashes.

Your party escapes in an airship that takes you straight back to Altair.