Yxnøy (also spelled Yxney, formerly: Yxnøyn) is the southernmost part of Østerøya (East Island) in Sandefjord, Norway. It stretches from Nordre Truber to Ertsvika. It is one of the largest undeveloped areas found along the Vestfold coast. It is a recreational area home to several beaches, steep cliffs, forests, sloping rocks, glacial potholes, hiking trails, and Tønsberg Barrel. The main trailhead is located at Tallakshavn, which has been named one of the most scenic beaches in the Tønsberg Fjord. There are marked hiking trails from the parking lot to Tønsberg Barrel and various beaches such as Strandvika and Ertsvika. Ertsvika is a sandy beach in the southern part of Yxnøy. This was the filming location for the 1993 film Head Above Water. A theory of this beach's namesake is the plant species Pisum. Another theory is that the beach is named for a species of seal. There are public toilets at Nordre Truber, Strandvika, Ertsvika, and Engebukta. It is home to a variety of trails, including to Tønsberg Barrel and a variety of beaches. Designated campfire sites are located at Nordre Truber. Islands near Yxnøy include Espeholmen, which as an elevation of 20 meters above sea-level and lies in the Mefjord outside Yxnøy. Teistholmen, Terneskjær and Torsholmen are three other nearby islands. Yxnøy is home to varied wildlife and a number of rare plant species. A 9 km trail from Yxnøy leads to the beach Skjellvika. It is part of the international North Sea Trail. Parts of southern Østerøya, the Skogan farm, was purchased by Christen Christensen in 1899, and the Christensen family has since owned parts of Yxnøy. The first property was purchased by Christen Christensen from Anders Kristian Hansen in 1899. The property was expanded in 1933 to 1,600 decares and was now the largest property in Sandar. From 1961, the owner of Yxnøy was Lars Christensen. The area was now also beginning to take shape as a nature park. Yxnøy and the area surrounding Tønsberg Barrel were fortified by the German occupation forces during World War II.