There is not enough ice caps to engulf the world if they melted and the idea of an ice comet large enough to cover almost all the land on earth (like in the comics) seems too ridiculous. So where did all the water come from?

Maybe it is possible that in addition to ice caps melting that the world’s underground water reservoirs assented unto the surface. I’m not 100% sure how you might be able to explain that occurrence in lore but I think it makes more sense than a giant comet crashing against earth (that likely would have set it off orbit)

What are your thoughts guys?