The area of Lapland region is 100,367 km², which consists of 92,667 km² of dry land, 6,316 km² fresh water and 1,383 km² of sea areas. In the south it borders Northern Ostrobothnia region, in the west Sweden, in the north and west Norway and in the east Russia. Its borders follow three rivers: Tana, Muonio and Torne. The largest lake is Lake Inari, 1,102 km². Highest point is on Halti, which reaches 1,324 m (4,344 ft) on Finnish side of the border.
The areas of Enontekis and Utsjoki in northern Lapland are known as Fell-Lapland. The bulk and remaining Lapland is known as Forest-Lapland. Lake Inari, the many fens of the region and the Salla-Saariselkä mountains are all part of Forest-Lapland. Fell-Lapland lies in the fells of the Scandinavian Mountains. Where it is not made up of barren ground like blockfields it has a vegetation of birch forests, willow thickets or heath. Common soil types in Forest-Lapland are till and sand with conifer forest growing on top. These forest show little variation across Lapland. Compared to southern Finland forest tree species grow slower. Understory is typically made of blueberry, lichens, crowberry and ling.
The landscape of large parts of Lapland is an inselberg plain. It has been suggested the inselberg plains formed in Late Cretaceous or Paleogene time by pediplanation or etchplanation. Relative to southern Finland Lapland stand out for its thick till cover. The hills and mountains are typically made up of resistant rocks like granite, gneiss, quartzite and amphibolite. The ice sheet that covered Finland intermittently during the Quaternary grew out from the Scandinavian Mountains. The central parts of the Fennoscandian ice sheet had cold-based conditions during the times of maximum extent. This mean that in areas like north-east Sweden and northern Finland pre-existing landforms and deposits escaped glacier erosion and are particularly well preserved at present. Northwest to southeast movement of the ice has left a field of aligned drumlins in central Lapland. Ribbed moraines found in the same area reflect a later west to east change in movement of the ice. During the last deglaciation ice in Lapland retreated from north-east, east and southeast so that the lower course of Tornio was the last part of Finland to be deglaciated 10,100 years ago. Present-day periglacial conditions in Lapland are reflected in the existence of numerous palsas, permafrost landforms developed on peat.
The bedrock of Lapland belong to the Karelian Domain occupiyng the bulk of the region, the Kola Domain in the northeast around Lake Inari and the Scandinavian Caledonides in the tip of Lapland's northwestern arm. With few exceptions rocks are of Archean and Proterozoic age. Granites, gneiss, metasediments and metavolcanics are common rocks while greenstone belts are recurring features. More rare rock associations include mafic and ultramafic layered intrusions and one of the world's oldest ophiolites. The region hosts valuable deposits of gold, chromium, iron and phosphate.