Could we fathom the great sea of existence of which we are merely a transient wave?
You know, that’s a good analogie for the way that presentism defines the past and the future. Presentism is the view that only the current moment exists, as opposed to eternalism, which states that, to borrow your terms, the great sea of existence (temporally speaking) is all equally existent. There is a theory in calculus that says that any single wave, no matter the shape, can be thought of as the addition of many other infinite waves. By studying the fine details of a particular wave, it would be possible, in theory, to calculate the whole of the ocean’s waves. Now the degree to which one wave actually affects the others in a calculable manner is tempered internally by the uncertainty principal and also by outside influences (such as the pull of the moon, which causes the shifting tides and is a major influence on waves). This is more of an analogy, as mathematics permits finite waves with no effects beyond the local. However, in physics, if you examine any small region of the world
