Both of these comment allude to the real issue. If you have to build something in a coastal city just so it can be on par with an inland city, that's quite a disadvantage. Which is fine, if you are offsetting some advantage you get with coastal settlement. So the problem right now is that there is no advantage for building on the coast, but lots of disadvantages. My memory is getting a bit fuzzy, but I recall that in Civ 1 you wanted to build on coasts and rivers because that was how you got trade. Also, there was no embarking, you had to build a transport to move troops off your continent, which meant you needed a strong coastal city (to build enough ships) to be able to project power overseas at all. I am kind of warming up to the idea of better Harbor adjacencies. I feel like the Harbor should also get benefits from City States somehow. Right now it is an odd mix between an Encampment, Industrial Zone and Commercial Hub. Maybe let Harbors and Commercial Hubs still give 2 Trade Routes, then let building a Commercial Hub next to your Harbor give you extra bonuses for Commercial CS envoys and ditto for Industrial Zones and Industrial CS envoys? Here's a thought - what if the shipyard was a separate District instead of a building? Unlocked with Apprenticeship, can't be built in a city with an Industrial Zone, gets the same/similar Industrial Zone buildings, gets a major Harbor Adjaceny, and you build it on coast tiles? The water park currently feels pretty nice because it doesn't take up a land tile. Its a little weird if Factories and Power Plants powering your entire city are in your dockyard, but I don't think that's too much of a stretch (shipyards generally have power plants, just not ones powering the entire city), especially if you're using most of that production for navies and such anyway. It might also be worth considering that, now that we have Canals, perhaps Harbors should be required to be next to a city. If you want to build ships from an inland city, you can - but not until later in the game, and not without expending resources and land tiles to the project.