When the laser shines light from air to water at a 45° angle downwards to the right, two things happen when the light hits the water:
1. The light refracts, or bends, as it enters the water due to the change in speed between the two mediums. This causes the light to change direction and travel through the water at a different angle than it was originally traveling in the air.
2. Some of the light is also reflected back from the surface of the water, which causes a portion of the light to bounce off the water's surface and return to the air. This reflection is known as specular reflection, and it occurs because the water-air boundary acts like a mirror for the light.
Together, these two phenomena explain why objects underwater often appear distorted from their actual location, as the light is refracted and reflected in various ways as it travels through the water.