((I'd say that prestidigitation could be used to ignite the webbing, but you'd have to be within range for the spell.))

((Cool. I won’t rewrite it, but we can take it that that’s what she means: she can ignite a web/kindling/torch/candle/etc, but she can’t spectacularly ‘hurl fire’. Thanks

And she’s happy to get close if that’s the party plan)).

((Or she can light a makeshift projectile… or arrow maybe))

Galingal looks around their meager collection of supplies. A lack of torches or oil make it difficult for them to ignite an arrow from range.

He just looks over at Lia and nods.

"Tell when close enough," Galingal says then looks at the others. "Get ready."

He begins polling the boat a little closer, keeping the pace as slow as possible. At the same time he keeps an eye out for any movement in the webbing.

As soon as Lia gives him a signal he jams the poll in to stop the boat getting closer.

When the boat is within range ((10ft)), Lia nods at Galingal and then lights the nearest web using prestidigitation…

((She will keep lighting and relighting any web within range until none is left within range, or until anything dramatic happens, or unless lighting the web might place her, the boat, or the party in danger of the flames)).

The web flares up, casting bright light in the eyes of you and your companions, and lighting up the cavern. There is a scuttling hiss towards the ceiling, as something chitinous and shiny retreats from the flame. Moving along the mouth of the tunnel, Lia keeps lighting it up, the flame rushing backwards into snarls deeper in the tunnel, guttering out in places where it's sparse, but flaring up and surging in dense places.

((Perception checks from those who wish to make one?))

Lia keeps a look out while she lights the webs…

Percrption: 23 

In addition to the web's inhabitant that is retreating in the face of the fire, Lia spots a few messily silk wrapped bundles that are strewn about the web, one of which drops smoldering to the water below. For the spider itself, she only sees one, but it is half the size of their boat.

Perception: 15

If Lia points the bundles out or if she notices them herself and the ones that fall she says to the KT,

"Go in there and check what that was that just fell in the water. Also check the bottom for anything else the the spider may have cast off."

To Lia she says,

"Drop those silk bundles if ye can reach them."

She specifically doesn't ask Neth, but does cast him a suspicious glance.

Galingal looks at the bundles falling.

”Lunch. Spider lunch.”

He keeps an eye out above in case the massive spider gets brave as they pass by.

The KT gulps, googly eyes rolling in his head as he gingerly hops into the water. He wriggles along the surface of the water, ducking under a few dangling strands of flaming web to surface near a small parcel bobbing on the surface and begins towing it back to the boat, arriving in short order and climbing back out to swing it into the boat.

To Galingal,

"Aye, but maybe its lunch had something of value to us. Aye'm not going to waste whatever this place can give us."

Stena eyes the package when it is onboard.

"And ye saw nothing on the bottom it may have cast off? Go check."

As the KT is doing as told she will pull out her short sword and poke at the silk before, as gently as possible, opening it.

((Give me a Persuasion or Intimidation check, with advantage. He'll do what you ask, but let's see how promptly.))

Stena is surprised by how light the sack is, it has a hollow give to it as she pokes it, and when she slices into it, she finds a desiccated, leathery set of remains, which seem to have had tentacles and a pointed body, maybe a few feet in length.

"Go."

Intimidation: 7

((Some dried shredded squid! Yum!))

"The spider looks to have been fishing."

((Not particularly fast it seems!))

Plibbleburp's eyes loll about in fear, searching the flaming web above for their maker. It seems less that he isn't willing to do as Stena asks, and more that he's not to keen about pilfering parcels from the spider's web. Not seeing the spider, he clambers over and lowers himself into the water, feeling a bit more secure in completing the request to search the water below than risk the spider above.

((Someone roll a d20 for luck on what Plibbleburp finds below the webs?))

Come on luck: 17

He returns to report that the are a bunch of weapons down there, dragging a trident over the edge of the boat.

"Missus dwarf want that I grab more?"

If Galingal understood undercommon, hearing Stena referred to as 'Missus dwarf' might have granted him the first smile of his very long series of lives. 

But other than a few directions he's picked up, he still doesn't understand the exchange but he does notice the trident.

He stops poling the boat along to let the KT bring up whatever else he finds down in the water.

"Yes. Focus on the swords first. We're going to move a bit further down stream so we're not under the web and you won't come up under it."

Sighing she turns to Neth,

"Go help him. The more we grab the more we can sell to the duergar."

To Galingal she explains her reasoning in common,

"No more than a few minutes, then we move on. Aye'll keep an eye out for the spider with Jimjar and Buppido while ye and Lia watch the water."