The Flói Nature Reserve is a bird and nature reserve located near Árborg municipality in Southern Region. It includes a stretch of the east shore of the Ölfusá River. The reserve measures roughly wide by long, with an area of about . It is an Internationally Important Bird Area as recognised by BirdLife International. It is all low-lying wetland, on average only above sea level, and is subject to seawater flooding at the spring tide. There are vistas of the surrounding mountains. The reserve establishment began in spring 1997 when Icelandic Society for the Protection of Birds was awarded funding from the Environmental Fund for Trade and its operation has received support from the Royal Society for the Protection of Birds from the UK.