What does it mean when you dream that you look into the bottom of the pool and you see three snakes intertwined and swimming in the deep end?

Dreams use figurative language to represent real situations, and the pool probably represents a choice - something the dreamer might be considering "plunging into." But the subconscious mind has detected something that the conscious, waking mind seems to have either missed or ignored. Beneath the surface, in the deep water, there are snakes. In the language of dreams, this represents some sort of danger that is not apparent "on the surface" - by superficial examination. The dreamer needs to consider the situation "in depth" to discover the unseen danger.