As the group presses on, there's a bit of confusion at the crossroads. Raúguey impatiently chooses a tunnel and starts things moving. Everyone else sort-of follows along, with various folk nervously eyeing the other tunnel. As always, the doughty hirelings take rearguard. Perfect time for a grue.
Rawon switches to sword and board, and follows the pair down the passage, pausing for a moment while Raúuguey squeezes his bulk past a narrow spot. "Another chamber in here, more water, smells bad!" calls the big man from beyond the choke point. Urúvion moves up behind Rawon.
Indeed, it does smell bad. Whereas the other pools you've found in the Caves have been clear and clean, apart from sediment built up on the bottom covering gods know what, this pool is a foul and opaque greenish-brown. A rough natural column rises near the edge of the pool, all the way to the roof, and beyond you can just make out a slimy, slick ledge rising six or eight feet above the water.
Meawhile Durego, Ingvild, and Locky have taken a look down the other passage, for passage it is. They can see there's another cave beyond, but none of the trio wants to venture into unexplored areas while the mainline fighters are poking around in the other chamber.
Raúguey and Grit are peering toward the ledge, trying to spot a way up or past that might not involve wading in the icky water, when something starts moving in the water. At first neither man nor dwarf notices the disturbance, but Rawon, who just squeezed into the chamber, does. "Hey guys, is that a spring or something?"
That's no spring. A swirling mess of brown and green rises from the smelly pool and begins to move toward the group on the bank. Was that an eye? A tongue?
The four nearest the pool are close enough to be aware of the potential threat. Those back in room (K) are not likely to know anything is up. Rawon is not surprised by the creature, but Raúguey and Grit are, giving Rawon and the creature a round to act before anyone else can jump in. Urúvion is mostly blocked by the people in front of him and the narrow choke point in the tunnel, but he could move through the gap if he so desired (or retreat).
The (E) / (L) chamber is a bit confusing. (E) is the highest, with the brown-shaded area being six to eight feet lower. (L) is six to eight feet lower still, so the entire area is like a giant stair step. There's water running off the edges of the brown-shaded area down into (L), and if you recall from above, there was water from a spring or some other source feeding into the pit in (E) from above. You can't really see the tunnel leading SW from the area between (E) and (L). You can't really tell how deep the pool is, because it's icky and green.