Sea has limited functionality in the early game, as the only building available is the fishers hut. From this building, a fisher can catch fish from the sea, with varying rates depending on the weather. Fishing is possible during all seasons and can yield a great nutrition output early on. Once the boat building research has been completed, it is possible to build cheap but small boats and send them on missions like fishing, collecting treasure, gathering cartography data to craft star maps, preparing expeditions to discover and take distant land using those maps, attacking pirates and plundering/conquering enemy land with your army by sea. Later researches unlock bigger and more expensive ships that are much better suited for goods/army transport and sea combat.