Why not a port/harbour and shipyard. Its could be good for a number of things.
1: When you go for adventure you can load the ship with 400 man and the travel only takes 10 m.
2: You should be ably to build different kind of ships. In PvP mode its possible to build patrol ships who defend your cost from invasions. Battle ships who take out patrol ships and battle against each other. Cargo ships who take home loots from invasions then you invade an other player (you should only win resurses when you invade some one and the size of loot depend of how many cargo ships you have)
3: I just think of a new idee. Explorer ship. Find a new island to explore and develop. Small island with few resources, Medium island with better resources. And hugh island with lot of resources. Sometime there is other player how has dicovery the same island as you. Its will be war at the island and resourses. Very cool idee
Idont know how this will work but it’s a suggestion to develop the game.
Sorry for my English. Its sucks!