Fladen, Approach lighthouse in Varberg Municipality, Sweden.

Fladen is a caisson lighthouse on the Fladen grund reef, about 17 km west of Bua in Varberg Municipality. The 26-meter tower stands on the northeast side of the reef at 57°13'N 11°50'E and carries a radar beacon. The reef itself covers roughly 100 km², with depths from 5 to 65 meters.

A lightship was stationed at Fladen from 1892 to 1969, moored by a 756-metre chain to a 2.8-tonne anchor. The first vessel served until 1967, when it was replaced by the lightship Ölandsrev, renamed Fladen. In 1969 a caisson lighthouse took over the station; it now runs on solar cells and batteries and carries a radar beacon.

The name Fladen comes from the reef itself: the lightship stationed here from 1892 to 1969 was renamed after the ground, with "Fladen" painted in large letters on its sides. The preserved lightship is now part of the Maritiman museum in Gothenburg, while the last one, in service from 1967 to 1969, was later moved to Stockholm and is used as a private houseboat.

The lighthouse sends out navigational signals visible from a considerable distance to guide ships safely through the area. Note that this is an active navigation structure in open waters, not a site for casual access.

The first lightship at Fladen, in use until 1967, was bought by Swedish film director Hannes Holm and gave its name to his production company, SS Fladen. The replacement lightship, renamed Fladen, became part of the Maritiman museum in Gothenburg in 1990.