Upgrading the Lighthouse
The Lighthouse can be built on day 17 and requires items found during expeditions on the World Map. By upgrading the Lighthouse, it becomes possible to scout even more area on the World Map, and the dense clouds will turn into a lighter fog. This fog can be cleared away by sending expeditions with your rafts, which can clear up the fog. You will see a spyglass icon if your expedition will clear away any fog, so keep an eye on those and plan your expeditions carefully!