IIRC water levels don't align on the 'Temperate' map. Swimming animation height also seems to be off on that map.A quick trick to find where the water levels are is to turn n global vertical snapping and place a one meter wall and use shift to raise or lower it. Once you have that in place you can then set the terrain to accommodate the desired water level. This works because the global snap is the same as the water levels.
Have not had that issue in my game. Note that some maps do not start at an even meter level. Which is why the shift to raise to the next snap first is needed.IIRC water levels don't align on the 'Temperate' map. Swimming animation height also seems to be off on that map.