ITEMS TO GET: Mermaid Mail, Dark Rod, DeathBlower 2

   Fly back to the Thames and talk with the Captain (on the bridge, as usual). He'll agree to help you get to Sargasso. Why? Because... He is! A man! Of the sea! There's also some new Gear equipment you can buy at the shop, though it's also available on the Yggdrasil (of particular note is the G-Matchlock gun for Renmazuo). Be sure to equip all your characters with D Circuits to boost their agility in water, since the next dungeon takes place underwater. Equipping some Gear accessories to boost your electrical defense would probably be a good idea too.

   When you're ready to leave, go to the bridge of the Yggdrasil, talk to Sigurd, and choose to depart for Sargasso (if you want to go elsewhere, just choose that option). The Yggdrasil dives underwater (maybe it's me, but I don't see how the Thames actually does anything here...) and you'll end up in your Gears underwater.

   First of all, if you want to go back up, just jump up and you'll return to the Yggdrasil. Moving around in Sargasso is kind of weird; you have to hit the jump button repeatedly to propel yourself forward through the water. Just head down the tunnel, following its twists and turns. Along the way you'll fight Medusoids, who have a high evade rate but little HP, thus making Deathblows the only way to kill them; and Death Scythes, which have a tremendous amount of HP -- again, use Deathblows as much as possible.

   When you reach the first fork, go right and you'll switch to a new screen. The Death Scythes will stop appearing here and be replaced with Mermen, submersible Gears that use electrical attacks. They're generally easier (though Siebzehn has a hard time hurting them for some reason), so this is a welcome change.

   At the second fork, take the eastern fork to a third screen. This screen appears to be a dead-end, but walk to the very end of the passage and start hopping around until you end up on another screen above water. Get the Mermaid Mail from the chest at the north end of the room, then go back underwater and take the west fork to the real third screen.

   This screen is populated mostly by Aragonites, annoying enemies that seem to be immune to both regular attacks and Ethers -- you have to use Deathblows to kill them. And once again, there's a fork in the passage; take the west fork this time (you'll have to fight through the current first). It will take you to another "dead end" room; again, jump up out of the water and into the cave Open the two chests. One of them holds the Dark Rod for Elly, and the other is actually a switch to stop the current below. Go back to the previous intersection and take the seaweed-filled passage to the east. As you walk through here, the screen will change, which can be disoriented (especially since you can't see your Gears between all the seaweed ^_^). Just keep going northeast until you come to another dead end. You probably know what to do here by now -- jump up the wall and out of the water. In this room, grab the DeathBlower2 from the chest and equip it immediately. Although not quite as useful as the DeathBlower1 (since you need to charge up two rounds to use it), it's still very powerful. Now de-equip all those D Circuits (you don't need them anymore), and equip any Wind Veil Armors that you have. Then go north through the big doors to the Gate room, where you'll have to fight Emeralda's Crescens.

   Emeralda has a variety of attacks: A physical attack (1200-1800 HP damage), lightning (around 1400 damage), and a throw move (1750 or so). Attack with the standard strategy: X button attack, Deathblow, X button, etc. Be sure to use your DeathBlower attacks! When Emeralda has lost about half of her 15,000 HP, her Gear's wings will droop. She will then start casting Anemo Omega (although it's not labeled as such), a cool-looking spell that hits your party for about 2000-4000 points of wind damage. If you've got Billy or Citan along, have one of them use magic (Chiseii / Earth Shield) to boost your wind damage. Otherwise, just keep up the same pattern, and stay healed up.

   When the Crescens is defeated, the Gate will explode. Your party returns with Emeralda to the Yggdrasil, where, after some dialogue, she joins "Kim".