The Site is characterized by tundra wetlands and palsa mires, forested and non-forested peatlands, permanent rivers, marshes and pools, all representative examples of natural wetland types in the northern part of the European Boreal region. The northern parts of the Site, especially the shores of the river Muonio, feature biodiversity-rich deciduous wet forests. Mannavuoma’s diversity of wetland types make for a rich animal and plant life; for example its flark pools are excellent habitats for birds, especially waders. The Site supports bird species included in Annex I of the EU Birds Directive, such as the red-necked phalarope Phalaropus lobatus and the Eurasian golden plover Pluvialis apricaria. The well-developed bog areas contribute to carbon sequestration. The Site is situated in an almost inaccessible part of the country, with large areas naturally protected by surrounding water; the main land use is reindeer grazing. Mannavuoma is one of seven palsa mires included in an environmental monitoring programme. Initial surveys show that the area covered by palsas has decreased since the 1960s or that they have completely vanished. The Site is adjacent to the Lätäseno-Hietajoki Mires Ramsar Site which lies across the border river in Finland.