Some things ain changing, yet some changed things. The sea will remain flat most of the time is one of them, but not hiding is no solution neither. Since ever, a fortress was better than a fleet, but noone builds forteresses anymore. The Bismark was sunk by a very manouverable airplane dropping a torpedo, wich is a diving weapon with a realy big warhead compared to e.g. a rocket.
Comunication within a fleet was always good until U-Boats came up lacking a spot for a guy with two tiny flags, but than from the right ancle they still can telegraphe by small light signals. Communication was enhanced and build up on ships, but only radio encrypted based, there is no fleet that can build a direct link laser beam system and certainly no ship that masters hitting a satellite with one during a storm.
Destroyers turned all rocket, even so artillery aiming systems using a computer guarantee perfect hits, fly in an ancle and therefore over obstacles, can be rather low cost mass produced and even be a combination of shell and rocket, while carrying more ammo.
Finally, some ships are stack piled with nuclear warheads and hitting them at the wrong position will turn this planet into an asteroid belt, pretty much as a since recently 24/7 over Arctica circulating bomber of the US Bomber Fleet just crashing down ripping the melting ice apart and this way creating a Tsunami we were told the Dynasors fell victim to.
The ants might not mind and collective intelligence could turn out better than big, fat and aggressive or individualistic intelligence for the ecosystem that still does not need us.
This being said, there is all in the arsenal to turn an important harbour into a fortress.
The core is the existing maintenance yards, the docks with all buildings. The premissis has two sides only: One to the sea and one to the land. These sides have a surface, a subwater and an airspace space attacks can come from. They have access roads and paths on sea and land, in the air and therefore most likely attack paths that must have forward defence positions relative to the expected range of attack weapons used. You can circulate above the Arctic, but are out over Pearl Harbour?
Most, actually all, modern fleet harbours disable the actual function of the ships and no Pilot ever landed on his carrier while in dock, no canon ever fired from a Frigat or Destroyer while towed to a solid concrete structure.
Then, the Army never saw any ships next to them, only all around. No MRLS ever took station along a coast line to guard 60km of open sea to limit an attack path down to a narrow direct ancle offshore and no tank ever was used with an artillery system to shoot in an ancle increasing the range to rocket levels from e.g. a forward island and only in cyberpunk runs an oilplatform would be used to land an autoloading tank or howitzer battery creating the first line of defence that will start shooting hot barrels, if the low passing jets dropped their load and the enemy still comes forward against the home base as soon as being in range.
