I took it to mean it is a river of humanity, the lives we all lead (or are mindlessly led) while in this world.

While in university, I had a somewhat similar dream: I was on an oceanside beach at night and saw several people running into the waves and back to shore pulling things out to lay onto the beach. When I got closer, I saw the "things" being pulled from the ocean were people, many of them children, and saw that the "ocean" was composed of waves of humans, all of humanity and the people on the beach were saving those whom they could, and I began helping. But realized immediately that even with my help the relatively small group would never be able to save everyone who made up that ocean of humanity. It was fascinating to see so many people that they came in waves and the overall mass looked like an ocean. That dream has stayed with me since, well, "college days". I take it to mean that although everyone can't be saved, some can, and I have a responsibility to help where I can.

Thank you for your reply.