"I can grab underwater but I can't swim!" Only Tencednil can understand her, of course. 

"If we tie a rope to Lhín, she should be able to collect seaweed as long as it is only minimially attached. Her ability to sever well-connected seaweed from the seafloor is minimal, and she would need to be pulled back up thereafter. If any of you have a pocketknife, she may be able to cut seaweed with that, but it may be too awkward a force for her to apply beneath the sea."

The enormous pack of stuff Julen has been lugging around includes a fifty foot long spool of rope. He gives the rope and a knife to Tencednil.

She has silk rope! Rope is useful, and silk is light. She will welcome his help in doing the lowering and tugging back up, though.

Knife, rope tied to Lhín — "Tomas, can you check this is secure? If it comes loose we may have a problem." — and knife to Lhín. She can't use it particularly effectively, but it should be enough to cut seaweed eventually.

He pulls on the rope a few times. "Seems secure to me."

Lhín goes doooown!

She can't really move well underwater. It's very strange. She can nudge herself around a bit, but if she tries to push at any real speed the water very quickly builds up and shoves her back. If she wanted to roll herself across the seabed she might be able to, very slowly. Fortunately her sorcerer has her on a rope!

Is there seaweed here? Does she recognize any of it as the kind she's supposed to be looking for?

A ring of jagged coral surrounds the hull of the sunken ship. Its decks are thick with blooms of seaweed, particularly near the wreck’s bow.

It all looks like the same kind, so probably it doesn't matter what she takes.

Grab! Tug! ...nope, too attached. Cut! Cut! Cut! And eventually, she grabs one bit of seaweed, and moves on to the next.

It takes her quite a while to collect seaweed. She's really not very good at cutting things. Eventually, though, she's successful. When the next Message whisper comes, she replies.

"Up now!"

She is not very strong, but Lhín is very light. Even with all her seaweed, this would be easy enough in air, and it's only more so underwater. She tugs Lhín, and seaweed, out of the water.

"Does this seem a sufficient quantity to all of you? We were not precisely given an amount, but soup contains only so much of its ingredients."

"That seems fine to me. That woman can't possibly eat much more in a single day."

"Then I believe we have what we are here for, and at a rather affordable price. Perhaps you should Purify it first? ...No, if she wished it Purified she would have asked." She starts walking back to the cabin.

They make their way back across the large island and over to the smaller island. At its center is a shade of willows and a mossy wooden hut. Plumes of smoke waft from the chimney.

She approaches the hut, bearing seaweed! (And she makes sure to set the Message back up, just in case.)

The sound of a bubbling cauldron can be heard through the closed door of the hut.

Knock knock? Well, more likely she leaves Yanor to knock, because she's carrying seaweed.

The door opens. She looks at them. "Alright, come in. Put the seaweed over there on the counter."

In! Seaweed on the counter.

"We cleaned out the skeletons, if you wish to collect seaweed yourself in the future." The right thing to do here is offer help with cooking, but she is a mediocre cook. Yanor might be capable? She tries to prompt him, as much as she can, but possibly he only knows how to Goodberry and never learned actual food preparation.

Yanor isn't an expert cook but he does know how to make do without goodberry. He's happy to help the strange woman with her stew.

After a little while, she introduces herself as Maroux. She's probably some sort of spellcaster. A spell component pouch and some potions are visible on one of the shelves.

The raven must be a familiar, then. She responds by introducing herself (is there a reason to lie here? No, and it will confuse the others, so she introduces herself as Tencednil), and leaves space for the others to follow suit.

Tomas and Julen introduce themselves.

"So, I hear you lot are looking for some sort of treasure inside the Lady?"

Yanor is cooking, and she's the one who is weaving their story. She'll take it. 

"We are! Yanor over there found a mention of its construction, and reason to think it was built originally back before the Starstone fell. It was in—" She cuts herself off, and somewhat awkwardly searches for a moment before continuing what probably was not her original sentence. "—the time of Sorshen, apparently. She somehow built it to resist everything that happened, and we thought that might well mean she built it to resist anything else in the meantime! Even if everything has been taken, there might be magic unseen in ages, and maybe the defenses have decayed enough for us to get something new!"

She definitely didn't say where Yanor found this mention. She certainly sounds like she came close to doing so, though.

"I did not know anything existed within the Lady. If you're lucky, whatever lives inside will be more friendly than what's typical around here."