Folhammar, Nature reserve in Gotland Municipality, Sweden.

Folhammar is a rauk field and nature reserve 3 km northeast of Ljugarn in Ardre parish on eastern Gotland. The rauk field itself is about 500 m long, with several limestone stacks reaching six metres, surrounded by pebble beaches. The reef limestone holds fossils, mainly stromatoporoids, "cat skulls" and crinoids. The reserve covers 77 hectares, 17 of them land, from the mouth of Halsgårdeån south to Vitvär fishing village.

Folhammar was protected as a nature reserve on 17 December 1974, covering 77 hectares: 17 hectares of land and 60 hectares of water. The reserve runs about 1.8 km along the coast from the mouth of the Halsgårdeån stream south to the fishing village of Vitvär. Its reef limestone, rich in stromatoporoids and crinoids, was formed in an ancient sea.

The place draws researchers and geology enthusiasts who study the fossil-rich limestone formations found here. Visitors can observe and learn about the ancient marine life preserved within the rocks.

The reserve is accessible by public transportation that connects to the Ljugarn area. Wear sturdy shoes since the rocky limestone surfaces can be uneven and slippery in places.

Stone and rocky beaches gradually transition into sandy shores both north and south, displaying different stages of coastal development. This mix of rock formations and sand beaches within a single location reveals natural coastal processes at work.