Ostøya

thumb | right | A large house in Ostøya Ostøya is an island in the western section of Oslofjord (Vestfjorden), within the borders of the municipality of Bærum. It is the second largest island in the Oslo basin, after Nesøya. It is adjacent to the municipal border with Asker, where Nesøya and Brønnøya are to its northwest and southwest, respectively. Within Bærum, Borøya is to the north, Kjeholmen to the northeast, and Grimsøya to the east. To the south is Gåsøya.

==History== At some point the island was split in two. The island is named after the farm that is situated on it. The etymology of Oust, or Ost is uncertain. O. Rygh claims the etymology is unknown but that the farm derives its name from the island's original name. Others speculate that it may have an Old Norse origin related to ouste, in the sense of claiming new land.