This nature reserve covers a part of the eastern bank of the River Olfusa estuaries, almost from the Oseyri Bridge to the boundaries of County Sandvikurhreppur.  It covers the greater part of the properties of the farms Oseyrarnes and Floagafl with a total area of 5 km², 1 to 1½ km wide.  This reserve, the Olfus Bogs and the estuary region of River Olfusa are counted among the internationally recognized bird sanctuaries.  Characteristic for the reserve are marshlands, pools and ponds and during the highest tides parts of it are flooded.  The average elevation above mean sea level is only about 2 m.

Debates on the recovery of drained marshlands and bogs have been continuous for several years and many societies have kept them alive.  The Icelandic Bird Lovers’ Society received a grant from the Nature Protection Fund of Commerce to initiate recovery measures in the area in 1997.  After having reached an agreement with the Eyrarbakki County Council, the work started the same year.  The Royal Bird Watchers’ Society in England has supported the project.

The Floi Area is situated on the so-called River Thjorsa lava field, which was created by fissure eruptions in the interior about 8000 years ago.  This lava field is considered the largest of its kind in the world of the Holocene Period.  The nature reserve is dotted with small lakes and ponds in the depressions of the lava field.  Remainders of the irrigation project completed in the twenties are still prominent in many places.  Its ditches were altogether 300 km (200 miles) long and the low dikes about 540 km (327 miles).  Close to two hundred small bridges and dams were built across them.  At the time, this project was the biggest of its kind in Europe.  Shortly after the irrigation system was finished the farmers all over the country started digging drainage ditches and a part of the irrigation system was altered to serve as such.

Old routes between Eyrarbakki, Kaldadarnes and Selfoss cut through Nesbru and Melabru in the eastern part of the nature reserve and in some places the well trodden paths are still very obvious.  Old ruins at Oseyrarnes were declared inviolate.  A short distance to the west of the old Floagafl farms, are quite a few peat quarries.  They are filled with clear and bluish coloured water and are the habitat of various small creatures and a variety of plants.  They actually combine the history of bygone ways of life and an interesting ecological system.

Waterfowl and other bird species characteristic for the reserve and the surrounding areas, especially during the breeding season (May, June) are: Whooper swans, greylag geese, mallards, wigeons (Eurasian w.), teals (green-winged t.), scaups (greater s.), tufted ducks and red breasted mergansers.  Nests of shovelers, pintails and gadwalls have been spotted, but these species are rather rare all over the country.  Eider ducks nest on the estuary islands and red-throated divers (loons) are spotted near the lakes and ponds.  There are also a few colonies of black headed seagulls and arctic terns, where many of the other prefer to nest for protection.  Only a few arctic skuas and herring gulls breed in the area.  Among other common species are dunlins, whimbrels, black tailed godwits, snipes, red-throated phalaropes and meadow pipits.  The golden plover prefers drier areas.  Nowhere else in the country is there greater density of dunlin nests and the same applies to the black tailed godwits.  During migration in spring and autumn (fall), the grey lag and white fronted geese (greater w.f.g.), wigeons and tufted ducks, several waders and wheat-ears (northern w.e.) are most prominent.

Harbour seals (grey seals) are common in the estuaries during autumn (fall) and winter.  They are most commonly spotted near the Kaldadarnes Islands, just off the nature reserve.  Minks are common the whole year round.  Sticklebacks, char and eels occupy the lakes, ponds and ditches.  In the estuaries mostly sea char, sea trout and salmon are caught seasonally.  Among the small creatures in and around the ponds and lakes are water beetles, amphipods, bugs and black flies.

The flora of the area is rich in species.  The marshlands are mostly covered with Lyngbye’s sedge and drier areas with woolly willow, tea leaved willow, common (black) sedge and common cotton grass.  Around most small lakes and ponds one can expect to find sedges, pondweed, grasses etc.  In the proximity of the peat quarries is among other plants the hair-leaved water-crowfoot.  In drier areas one can expect to find wild angelicas, Iceland rush, cuckooflowers, red fescue, sea peas and many other species.

Two species of beautiful and rather rare flowers are commonly seen in the nature reserve.  Devil’s bit scabious is found scattered about and also further east in the Eyjafjoll and Myrdalur areas, especially in the green slopes facing south.  Chickweed, rather common in the reserve, has only been found in wooded areas of the eastern part of the country.

Two old routes cross the nature reserve.  One is a road heading north from the village Eyrarbakki, past the farm Solvangur.  Two parking areas, on east and north of the Oseyri Bridge and at Stakkholt, offer people the possibility to use the hiking path on the riverbanks.