The Soul is like the Ocean
The Ocean is broad and deep, ever flowing and moving. Like our souls which are bottomless and vast, we are beings that process and progress. The ocean ebbs and flows changing course with the energy of the moon. Bringing things in and taking things away but consistently replacing and moving energy. Similarly the soul experiences a time of calm as well as a time of overwhelming swells.
Crashing waves represent the surges in emotions in our lives. Just like a situation that arises in life; nothing lasts forever, joy and sadness. Waves are formed on the surface of the ocean which causes turmoil under the surface. No matter how big or small they crash at the surface in order to absolve the displacement of energy. (maybe an anecdote here?)
Like anything, when water sits too long it becomes stagnant. If you think of a water basin, its water lays dormant and unmoving unless the tide reaches it. Movement depends on a flood or surging tides. The soul needs movement and needs to be wading through growth, experiences,healing, there is always something to be done. The ocean is calm, choppy, gentle, and cosmic.
Water is one of the most expansive elements because it is one that has moved through the Earth in all of its phases. Water itself is primordial just as our souls, they were here before our physical bodies and they will outlive them as well.