>>32948405I think Melemele to Akala Island would be fine
Just looking at the map and ignoring scale, th distance is about the same length as Hau'oli City
Whatever ocean area they add, they just need to treat it like any other route, maybe we can find Ace Trainers or Sightseers on Parasails or Sailboats and they challenge us using types that arent water types to break up some of the monotony
Throw in a Ride Pokemon that lets us Dive too, like Lanturn or Mantine or Tentacruel