A buoy lantern / lighthouse that is adapted for tough conditions. The lantern's high efficiency and robust design make it ideal for buoys and lighthouses in exposed places with harsh weather conditions. The lantern is designed to work for 10 years without maintenance. The lens is cast in one piece in UV-stable polycarbonate, which guarantees a lasting brightness and minimizes the risk of the lens fading or discoloring as it ages. Compared to traditional 85mm lantern with filament, LED160 shines about 5 times brighter at the same consumption. The lantern's high efficiency makes it excellent for installations with supply via, for example, solar panels.