Water expansion idea

I have an Idea that expands the naval warfare. I think it needs a lot more considering all it has is ships and fish traps. First I think they should let you build the sea walls in a regular match with something like a worker boat. First though they would need to change the model so there's no more ground at the bottom. I think another cool idea would be a land unit similar to the the strength of Man at arms but costing more like a champion. The benefit is that they can swim, eliminating the use of transporting similar troops if you are willing to pay more gold. I also would like to see a buff to the galleons because personally I think they're a little weak. Finally, this one I really want, is battle ships. They would be massively expensive, but would add population space, be very powerful, and could be used to attack (and be good at it too). It could also be able to transport things and hold more then a transport ship. I think the only way to balance this is to make it cost more. It would be roughly inspired of Japanese warships from the time that had temples in them. I'm open to criticism or critique if you have any.