The big Island Pool is heated. It's not bath-water warm but it's warm enough to swim in cooler weather, IMO.
It's sort of a combination pool - a large lap pool attached to a rectangular general pool area. The configuration is shaped like a big reversed "L" with the lap pool represented by the vertical part of the L. The end of the bottom part of the L runs into the back side of the sauna building with a waterfall coming from the width of the top of the sauna building down into the pool.
We've used that pool during a number of our February visits, when it can be pretty cool outside, and found the water temperature to be comfortable.
Dick Taylor