Eldgarnsö Nature Reserve
Location within Stockholm County
Location	Sweden
Nearest city	Ekerö
Coordinates	59°26′13″N 17°39′07″E / 59.43694°N 17.65194°E / 59.43694; 17.65194
Area	490 ha (1,200 acres)[1]
Established	1979[1]

Eldgarnsö Nature Reserve (Swedish: Eldgarnsö naturreservat) is a nature reserve in Stockholm County in Sweden.

Eldgarnsö Nature Reserve consists of Eldgarnsö island in Lake Mälaren. A 6-kilometre-long (3.7 mi) trail runs around the island. The nature reserve consists of on the one hand an area of broad-leaf forest, and on the other of an area which is more mixed, containing arable land, coniferous forest and beach meadows with shallow water overgrown with reeds.^[1]

The broad-leaf forest is dominated by oak, European ash and wych elm. Mistletoe grows among the trees; this parasite is uncommon in Sweden (and hence a protected species) due to the cool climate, but survives in local areas of warmer micro-climate such as Eldgarnsö island. In the open meadows, solitary oak trees rise above stands of unspotted lungwort, Cardamine bulbifera, spring vetchling and black pea.^[1]

The island has a rich bird-life. Species include the European honey buzzard, Eurasian wryneck and ortolan bunting. The nature reserve also supports a rich variety of insects.^[1]