Rya Forest, Nature reserve in Gothenburg Municipality, Sweden.

Rya Forest is a 17-hectare nature reserve on Hisingen island, on the north bank of the Göta River. It protects a remnant of the mixed oak forest that once covered the Swedish west coast, with alder as the most common tree and oaks several centuries old. The oldest known document mentioning the forest is a 1678 drawing by Erik Dahlbergh.

The forest was first mentioned in a 1678 drawing by Erik Dahlbergh. In 1916, when 28 oaks were advertised for sale, the Gothenburg branch of the Swedish Nature Conservation Society protested, and the reply restricted felling to dead and wind-felled trees. After further campaigns, Rya skog was protected as a nature monument on 3 February 1928, with a proclamation issued on 12 April 1928.

The forest is a remnant of the mixed oak woodland that once covered the Swedish west coast. It has long been a destination for botanists, ornithologists and school classes, especially in spring when wood anemones bloom. A 2007 survey recorded 22 threatened and rare species.

The reserve is open year-round. Paths can be muddy and uneven, especially in the marsh forest, so waterproof footwear is useful. The forest is surrounded by the Ryaverket sewage plant and oil refineries, and the historical link to the Göta River at Rya Nabbe is cut off, so follow marked routes and do not expect river access.

Despite being located next to industrial facilities including oil refineries, the woodland supports populations of rare insects, lichens, and mosses. This biodiversity demonstrates nature's ability to persist in developed industrial environments.