Steep mountains near the sea and an almost flat lowland area in between the mountains and the sea ("Strandflaten", coastal brim) is very typical for the long coastline in Nordland, and "Strandflaten" often continues out from the shore, the result is numerous islands (skerries), of which Helgeland have thousands; these islands are usually mountainous, but with smaller or larger "strandflate" areas. The southern part of Norways largest island (apart from Svalbard), Hinnøya is in Nordland, as is the third-largest island, Langøya. In the fjords, the coastal brim is much less developed: There might be a more gradual slope, with hills, towards the mountains, or no lowland at all. There are often valleys at the head of fjords (the fjord is an extension of the valley), usually with a river at the centre of the valley.