hi! this is the right forum to ask that!
first off, there are a ton of different maps for this game; and unfortunately the game doesnt give you the option to pick the one that you want. I spent ages shutting my game down and resetting it in order to get my preferred map. so if layout also matters? you've got to do that. if there's another way to do it please let me know bell tree folks!
secondly; you can terraform your island to match whatever you choose it to be, even if you've gotten a map that you dont like HOWEVER! the river entrances, docks and airport locations cannot be changed.
if I were going for an ocean themed island, and wanted a pond that matched that theme? maybe a fish shaped one would be small enough? or maybe a shark?
good luck! I would love to see your island when youre done!