According to this diagram:
And a few articles I have read, the number of photons emitted from a point source is exactly the same, and the reason why we detect fewer photons as we move away from the source is because the photons spread over distance. If that's true, then why is there specific distance that light can travel in a medium like tap water (2 m) or distilled water (8 m) or ice beneath the south pole (about 100m - 200m)? Is it because photons are absorbed by that medium? And if I were to have a point source in "total" vacuum which emitted about 10,000 photons. If I went away from that source by 1 kilometer or two and surrounded the entire source by a sphere, will I detect all of those 10,000 photons?