Step 1: Setting of the pool.
In the lesson "Deep Water," the Y.M.C.A. pool is described as a place of both fear and fascination for the narrator. It was an indoor pool that appeared intimidating to him as a young boy who had never learned to swim.
Step 2: The narrator's first experience.
The narrator recalls that he was terrified of the pool's depth. As he had a fear of drowning, the pool seemed like a vast and threatening body of water. His initial experience was filled with anxiety as he felt out of place in the water.
Step 3: Conclusion and significance.
However, as he learned how to swim and overcame his fear, the Y.M.C.A. pool became a place of empowerment. The pool symbolized his personal growth and the triumph over his earlier fears, transforming from an object of dread to a place of confidence.
Final Answer: \[ \boxed{\text{The Y.M.C.A. pool in "Deep Water" symbolizes both fear and triumph. Initially, it was a terrifying place for the narrator, but as he learned to swim, it became a space of confidence and self-discovery.}} \]