The ocean of samsara is literal. It’s not a metaphor. The ocean is composed of many water molecules. The water stores information. It stores memory. It stores the memory of all of human existence. It stores the memory of samsara, the cycle of birth old age sickness and death. It reinforces this pattern and this cycle.
The cycle is conditioned into the very fabric of our being, as humans are made mostly of water. Humans add to the cycle by continuing to dump both literally (trash, chemicals, etc.) and metaphorically (by repeating the conditioned pattern) into the ocean. Not taking responsibility for our behavior. Failing to see the consequences of our actions and mindlessness. Repeating the suffering through our own ignorance and sleepy way of living.
It’s just as literal and real that one person waking up changes the content of the ocean. As one person touches into his/her basic goodness, the water molecules in his/her body change. All water on our planet is the same recycled material, so the person’s changed water molecules make their way back into the ocean through the breath and other bodily processes.
A group of people touching into basic goodness have an even more powerful effect on the ocean, little by little turning it from a sea of samsara to something more. A pool of bodhichitta (awakened mind) that serves to strengthen and uplift human beings and the world into their own true nature of basic goodness.