The region in the aquatic environment where light can penetrate is called the photic zone.

Here's a breakdown:

* Photic Zone: This zone extends from the surface of the water down to the depth where sunlight can still support photosynthesis. It's also sometimes referred to as the euphotic zone. The depth of the photic zone varies depending on factors like water clarity, latitude, and time of day.

* Aphotic Zone: Below the photic zone is the aphotic zone, where there is no light for photosynthesis.

Let me know if you'd like more information on the photic zone or the different zones within an aquatic environment.