Lake Simojärvi is Finland's 50th largest lake. It covers an area of 97 sq. km and is about 40 km long. Lake Simojärvi is in its natural state meaning that the level of water in the lake is not regulated by humans. There are several small rivers which flow into the lake. For example the waters of the Rivers Paasonjoki and Paha-Paasonjoki through which the waters of Lake Paasonjärvi flow into the River Paasonjoki play a part. The waters from these rivers flow through Lakes Yli-Soppananjärvi and Soppanajärvi and down the River Soppananjoki into Lake Simojärvi. The waters of Lake Simojärvi then flow down the River Simojoki into the Bothnian Bay.
The majority of Lake Simojärvi is part of the Natura 2000 network and most of the lakes shores and islands are areas protected by the Shore Conservation Programme. There are about 40 islands of varying sizes in Lake Simojärvi the largest of which is Porosaari Island. The lake is known for its crystal clear water and its depth which is at its deepest point 28 metres. There are also numerous shallow spots and reefs in the lake, which pose problems for boaters. A typical characteristic of such a rugged lake are sandy beaches of which there are many around Simojärvi. Lake Yli-Soppananjärvi which is nearby is great for fishing and has many sandy beaches that draw swimmers. There is no official beach.
Rock Bed and Soil
The rock bed in the Simojärvi area is made up of granite, migmatite and granite gneiss. The landscape is gently sloping. The shoreline is moraine covered for the most part paludified. There are open rock faces and steep cliff walls on Paasonvaara Hill and on the south side of Lake Tuppilampi.
The old-growth forests in the Soppana area are part of the Old-growth Forest Conservation Programme as well as part of the Natura 2000 network. The Soppana area forests have been shaped by numerous forest fires. In some places there are pine forests which are almost in their natural state. Small spruce forests are also common in the area, which have microclimates that are ideal for demanding species. There are also some herb-rich-like heathland forests here.
The mires along the shoreline of Lake Simojärvi are pine bogs. The mires in the Soppana area are for the most part sedge dominated open bogs. There are also small fens in the area. On river banks the mires are for the most part pine and spruce bogs. Mires are popular cloudberry picking places. When cloudberries are ripe there are many berry lovers in the area.
Species in the Simojärvi and Soppana Areas
The vegetation in Lake Simojärvi belongs to the elodeid biotype, which means that the most common vegetation in the lake are totally submerged in water and include fragile long stemmed grasses and water moss. Vegetation which reaches the surface of the lake is sparse; for example there are only few reed beds and they are narrow. The mires along the shoreline are for the most part pine bogs. Fresh heathland forests are the most dominant forests in the area. In general the vegetation in the area is rugged. The vegetation in the Soppana area is dominated by species typical of fresh heathland forest.
The bird population in the Simojärvi and Soppana areas is diverse. In the Simojärvi area there is a large Arctic Loon (Gavia arctica) population and other water birds are found on the lake as well. Some young Swans (Cygnus cygnus) are also a part of the birdlife of Simojärvi, but they do not nest in the area. The Osprey (Pandion haliaetus) is the bird of prey which hunts in the lake area. Great Cormorants (Phalacrocorax carbo) have also been seen in the area.
The Soppana area's bird population is made up of species which are typical of coniferous forests. The Siberian Jay (Perisoreus infaustus) may come to greet hikers while they are resting by the trails. The forest tetraonid population in the area is thriving.
Simojärvi is also a valuable spot for its fish population. Thirteen fish species can be found in the lake including the white fish (Coregonus lavaretus sp.), the vendace (Coregonus albula), the lake trout (Salmo trutta) and the grayling (Thymallus thymallus). Also the Atlantic Salmon (Salmo salar) may swim up the River Simojoki into the lake.