I have the alpha on my sea texture set to 0.375, blend mode to Alpha Blend, and backface culling and show backface are both checked. I need the sea to be transparent to the point where you can kind of see through it, but dark enough to the point where it looks like, well, the sea. Kind of like most common low-poly sea models out there.
Also, the points where you see the sea floor through the sea are the point where the sea floor plane ends. I don't know if that helps or not, but there ya go
EDIT: turns out I was in eevee. it worked as soon as I just changed the render engine to cycles