Light particles have no mass. The physical laws embedded in our universe dictate that massless objects can only travel at roughly 3×10^8 m/s. You can think of it as the cosmological speed limit if you will.

In terms of your comparison, yes any object would travel faster in a less dense medium (i.e. air) than a more dense medium (i.e. water). Which is why you see distorted images in water (the light particles slow down when they hit water)

However this 3×10^8m/s speed limit is measured in a vacuum, i.e. a region in space devoid of anything. So theres nothing really slowing down these light particles they are simply just moving as fast as they possibly can as dictated by the laws of physics embedded in the fabric of space time.

If particle of light can travel on it’s maximum speed limit that we call _speed of light_ then what is with space that allows this to happen ?? Why ? Well there must be something that work as obstacle to traveling particle that won’t let them go faster. We know friction mechanic and how it work. This is like speed boat. It is water vehicle but 90% of it is in the air. If speed boat is air vehicle it would be dozen times faster. I guess it can’t be cos only the mass.