Furillen
| The old  limestone factory building on Furillen | |
| Geography | |
|---|---|
| Location | Baltic Sea | 
| Coordinates | 57°46′7″N 19°0′55″E / 57.76861°N 19.01528°E | 
| Area | 4 km2 (1.5 sq mi) | 
| Length | 5.3 km (3.29 mi) | 
| Width | 2 km (1.2 mi) | 
| Administration | |
| Additional information | |
| Official website | www | 
Furillen (older spelling Furilden) is an island in Rute on the northeast coast of Gotland, Sweden. For most of the 20th century, there was a limestone industry on the island until it was closed to the public by the Swedish military in the 1970s–90s, when radar installations became operational. The north part of Furillen is a nature reserve and a Natura 2000 area.