When Ishzu gets closer the middle, it drops to about three feet deep, but the deepest part appears to be a relatively small hollow (no more than 20x20. Most of the slime is only one to two feet deep. If you stay along the walls, it's only a few inches. However, when Ishzu moves into the hollow he bumps into something in the hollow. It seems to have a mass roughly that of a large human, but it is definitely not humanoid in shape. In fact, it seems to not really have any particular shape. It can be moved, however, as it moved when Ishzu bumped into it. But that movement was purely do to the impact of Ishzu's contact; it is not moving of its own volition or anything.
Grin looks around their side of the pool and finds a very odd looking set of items. They look like long boots, long gloves, and a mask that covers the eyes, nose, and mouth of a goblin. Despite obviously being made for a goblin, the boots and gloves look a bit oversized (but still not big enough for a human, or even a dwarf). It's like the boots and gloves are intended to go over a goblin's normal clothes. Grin can easily use the boots and gloves if he wants; they are close enough fit. The mask won't work as well, but it would suffice.
OOC:
For a modern human equivalent of the boots and gloves, think of knee-high boots rubber boots and those "rubber" elbow-length gloves moms would use in the sixties to protect themselves from caustic cleaning supplies.
As for the burn mark, it doesn't really matter. Imagine burning a spot on the surface of an algae clump. Sure, that piece of the surface is burnt and damaged, but it's pretty irrelevant to the rest of the clump and doesn't change the (lack of) surface tension on the clump. If you step on the burn mark, it would be like it wasn't even there; you foot would go right to the rocky floor.
Two more quick items just to help a bit:
1) It is better to scrap the pink slime off. Water just doesn't do a great job of washing it off. It sticks to itself pretty well, so when you do scrape, it tends to peel off in sheets, to an extent. Water might help with the final bits, but the first 95+% needs to be scraped off.
2) The water from the pool simply becomes clear potable water when taken away from the pool. The magic is in the pool; it doesn't follow the water. I'll just say it came up as a side comment from Fiznik while pontificating at some point or as a side note from Skeeve when you socialized back in the tavern.