I take photos, and I am not very good, so I absolutely refuse to up the saturation, so as to force me to learn to be better. I can show you a couple example photos from the air of lakes in the area, including looking down at the Spirit Island area.

First, looking down at Spirit Island: https://i.imgur.com/koOVWgu.jpg

The difference with mine is you're not seeing any low angle reflected light, but the blue is absolutely there, and intense. If you look carefully you can see shallow areas, the mud and weeds below look slightly darker. But yeah, with a low sun, you'll get a lot of reflection off the water, and the blue is even brighter. In my photo there is some blowout on the snow on the ridgeline closest to the plane, so the rest of my photo, water included is probably a little underexposed.

Here is my own groundview capture of Spirit Island on a rainy, foggy day. https://i.imgur.com/o8ptCMB.jpg

Here is a smaller lake via plane. Its also a higher elevation, so there is less silt in the water, and the blue is more intense, like a sky blue. In the right situations, those lakes are intensely, intensely blue. https://i.imgur.com/9MddmZh.jpg

Here is a lake off the foot of the Columbia Glacier. https://i.imgur.com/jFV8vzf.jpg