The Baldur's Gate 3 Iron Throne prison is one of the most memorable sections in the game, as you work against the clock to save a bunch of prisoners in Gortash's underwater prison. You see, the city's new archduke is forcing Gondians to build his army of Steel Watch robots, and is guaranteeing their obedience by keeping their families in a secret underwater facility.
But when you rock up to save them, Gortash decides everyone's better off dead, and so sets the place to self-destruct. It's a race against time as you try to save as many as you can, while also looting anything not nailed down and fighting the fishmen who've broken in. Oh, and Wyll's father is also stuck in a cell. Here's how to get to the Iron Throne as well as some tips to give you a fighting chance in saving the prisoners.
How to get to the Iron Throne
Gortash's underwater prison is only accessible via submarine, so you need to head to the docks. Find the Flymm's Cargo warehouse and break in, though watch out for the four Wargs standing guard once you're through the doors. Now, use the hatch hidden under the boxes in the northwest corner of the room to climb down to the basement.
Keep going straight on then take a left turn when it appears, and you'll find yourself in the submarine dock. Say a quick word or two to Redhammer the Deviser by the hatchway and he'll agree to take you to the Iron Throne. Upon docking at the prison, Gortash will send you a message threatening to blow it up if you don't leave, which leads to your current predicament of getting out as many hostages as you can before things go boom.
How to rescue Duke Ravengard
When you arrive in the Iron Throne prison, you'll have six turns to free as many prisoners as you can and get back to the dock before the whole thing explodes. While saving Gondian prisoners is important, Duke Ravengard is the real priority, since rescuing Wyll's father lets you continue his quest in the Wyrmway. Climbing down the ladder into the main prison, you'll want to head east toward the three cells at the end of the corridor. I used Shadowheart for this with a couple of minions to keep the Sahaguin enemies occupied. Duke Ravengard is in the central cell, which can be opened using the lever next to the door.
Now, if you chose to free Wyll from his contract in exchange for his father's life, Mizora will show up and try to kill the duke as soon as he exits, summoning some explosive spiders. I used Shadowheart to cast Sanctuary on him, and then Dimension Door to teleport past the spiders for safety. Get him onboard the submarine and he'll be safe.
How to help the Gondians
The trickiest part of the Iron Throne is saving the Gondian prisoners locked in cells throughout the prison, and getting them back to the dock before those six turns are over.
The Gondian Hostages are marked as objectives on the minimap, so are easy to find. Besides the hostages in the central room with you, the two main concentrations are to the south and the west, while Duke Ravenguard is to the east with some other hostages. The good news—though not for the hostages—is that you only need to rescue a few to convince the Gondian's in the Steel Watch Foundry to rise up, letting you continue the quest to destroy it, and get to Gortash with ease.
There are a few tips that can help you handle this, though:
Use spells to move quickly
Whether it's Misty Step, Dimension Door, or even just Fly, the quicker you get to the prisoners and let them out, the faster they'll dash back to the submarine and safety. Gale can be pretty invaluable here since his Arcane Recovery will let him cast an extra Dimension Door, as will the Markoheskhir Legendary staff if you've got it.
Bring minions
The Sahaguin enemies will keep spawning periodically, so it's better to keep them occupied instead of trying to kill them all. Minions are a great method of distracting enemies. I used the Danse Macabre ability you get from the Necromancy of Thay, which lets you summon six ghouls who can potentially paralyse enemies with their attacks.
Don't worry about companion deaths
There are a fair few valuable items to grab in the Iron Throne, including a Mind Flayer Parasite, so be sure to send a character off to loot everything. It's unlikely they'll make it back to the sub in time, but you can just revive them with Withers afterwards. The most important thing is that your main character is at the submarine when your time is up. If you're searching for treasure chests, your main port of call should be sending a character north, then west down the corridor, plus south and then west down that corridor.
Save Omeluum—if you can
You may have met this Mind Flayer in the Underdark, but it seems a bit inconsistent as to whether he actually shows up as a prisoner on the Iron Throne. If he's there, you'll find him in the room directly to the southwest with the operating chair, next to the flooded corridor. Sadly, this makes him the hardest character in the prison to rescue, since he's so far away, but if one of your characters is looting that area already, it shouldn't be too hard to free him. Omeluum also has a spell that lets him teleport back to the submarine with one other character.
