(Psychological / emotional perspective)
In order to understand ourselves we may need to explore the pool by totally immersing ourselves in it, that is, to become involved in our own emotions. How we deal with what arises (in more senses than one) will teach us a lot about ourselves.
The pool may suggest a form of cleansing, particularly of old traumas and emotions or of past misdeeds.
The most potent image of that is baptism by immersion.