I also had to test the sauna at my meeting hotel, the Marriott Marquis Queen's Park Bangkok.
They had two pools, one on the 9th floor and another one on the 4th floor. On the 9th floor there was also a gym and changing rooms and saunas. There were two saunas, one Turkish and one traditional Finnish sauna. It wasn't too hot, but quite nice.
The 9th floor pool was also nice, looked very shallow, as it started shallow on the outsides, but was actually deep enough to properly swim in.
The pool at the 9th floor at night:
The pool at the 4th floor: