Though most of the mine is flooded, there are a few areas that are not: The small room areas that Shaleez uses as a living area, and a larger area in the largest room in the mine. The only way to reach this part of the room is to find the wooden plank leading down into the water. One has to use it as it's not possible to jump out of the water up on the ground.
There are a few chests to loot in the mine with minor loot such as and potions.
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