Here's a breakdown of why:
* "Treacherous" implies danger: It suggests something that can't be trusted, that could lead to harm or loss. In the poem, the pool is the speaker's past, which is filled with memories that are painful and difficult to confront.
* Memory as a pool: The speaker compares memory to a pool of water. The image of a pool suggests depth, stillness, and the potential for submersion. In this case, the "depth" of the pool represents the speaker's past, the "stillness" represents the way memories can be trapped, and the "submersion" represents the potential for being overwhelmed by painful memories.
* The speaker's struggle: The speaker is wary of diving into their past. They recognize that the memories within are potentially "treacherous" because they can lead to emotional pain and distress.
Therefore, "treacherous" effectively captures the speaker's fear and hesitation to delve into their past, highlighting the potential danger and emotional turmoil associated with their memories.