the regular rise and fall in the level of the sea, caused by the attraction of the moon; a change in amount (of public opinion, feeling etc); to help a person to get through or survive (a period of difficulty etc)

flow, current

a current of water flowing beneath the surface; a tendency (of thought or feeling) below what is apparent

drift, pull

a place where there are circular currents in the sea etc (pulling floating objects towards its centre)

spinning water