Once a player has build the docks area door (Preferable not like this but on a placeable that would exhibit a dock like entrance) They can use the area to allow players to and from your area via boats.
The dock has a broadcasting Sign.
If a player has a built ship they can then use it to dock it at any docks.
The ship will appear when you goto the dock transition with a ship item in hand. Each ship is UNIQUE to the ship item in hand. If you loose that ship item you loose THAT ship instance. Make sure you do NOT loose that item.
The ships can sail to any location you choose or choose a random location that is procedurally generated amongst 100 types of location that randomly generates dungeons, loot, ore rarity and encounters. Making the trips either very easy or very difficult. You may even come across villages, cities and much more.
Travelling usually takes a LONG time without fuel for the ship engine. Typically the fuel used is coal, branches of oak and other wood types. As the engine heats up the faster your travel would go. However It is VERY possible to sink your ship by overheating the engine and exploding it. Insta-death Keep that in mind. There is a temperature bar on the engine once you put fuel in there.