The phrase "diminishing tides" can be described with a variety of synonyms to convey its meaning in different ways. Some potential options include "waning waves," "fading currents," "ebb and flow on the decline," or "receding sea levels." Each of these phrases emphasizes a slightly different aspect of the phenomenon, focusing on the idea of decreasing strength, lessening intensity, or decreasing water volume. Depending on the context and desired tone, any of these synonyms could be appropriate for describing the diminishing tides, providing a more varied and nuanced way of expressing the same idea.