Question: For which feat of endurance is the Norwegian explorer, photographer, writer and former deep sea diver for the oil industry whose diving was mostly carried out in a marginal sea of the Atlantic Ocean located between Great Britain and Scandinavia and whose name is Børge Ousland, best known?

Context paragraphs:
Leigh Bishop: Leigh Bishop (born 17 April 1968) is an explorer and deep sea diver known for his deep shipwreck exploration and still underwater photography.

Philippe Jeantot: Philippe Jeantot (born 8 May 1952 in Antananarivo, Madagascar) is a French former deep sea diver, who achieved recognition as a sailor for long-distance, single-handed racing and record-setting.  He founded the "Vendée Globe", a single-handed, round-the-world, non-stop yacht race.

Chaceon quinquedens: Chaceon quinquedens, commonly known as the Atlantic deep sea red crab, or simply Atlantic red crab or red crab is a deep sea red crab in the Atlantic Ocean off the East coast of the U.S. state of Virginia.  According to the Virginia Pilot, the species resembles a snow crab from Alaska.  Size-wise, the crab is about five to seven inches across the back of the shell and weighs about one to two pounds.  The crab is available from North Carolina to Nova Scotia along the east coast.  Many fishermen catch these as a by-catch in their lobster pots.  By chance, one of the fishermen tried cooking it and "discovered how tasty one was".  The crab had only started getting popular in the year 2013 and is making a name for the Hampton Roads area as a sustainable seafood business adding one more seafood option to the area.

Greenland Sea: The Greenland Sea is a body of water that borders Greenland to the west, the Svalbard archipelago to the east, Fram Strait and the Arctic Ocean to the north, and the Norwegian Sea and Iceland to the south.  The Greenland Sea is often defined as part of the Arctic Ocean, sometimes as part of the Atlantic Ocean.  However, definitions of the Arctic Ocean and its seas tend to be imprecise or arbitrary.  In general usage the term "Arctic Ocean" would exclude the Greenland Sea.  In oceanographic studies the Greenland Sea is considered part of the Nordic Seas, along with the Norwegian Sea.  The Nordic Seas are the main connection between the Arctic and Atlantic oceans and, as such, could be of great significance in a possible shutdown of thermohaline circulation.  In oceanography the Arctic Ocean and Nordic Seas are often referred to collectively as the "Arctic Mediterranean Sea", a marginal sea of the Atlantic.

Prince Gustav Adolf Sea: Prince Gustav Adolf Sea is a marginal sea of the Arctic Ocean located in Qikiqtaaluk Region, Nunavut, Canada.

Amundsen Sea: The Amundsen Sea, an arm of the Southern Ocean off Marie Byrd Land in western Antarctica, lies between Cape Flying Fish (the northwestern tip of Thurston Island) to the east and Cape Dart on Siple Island to the west.  Cape Flying Fish marks the boundary between the Amundsen Sea and the Bellingshausen Sea.  West of Cape Dart there is no named marginal sea of the Southern Ocean between the Amundsen and Ross Seas.  The Norwegian expedition of 1928–1929 under Captain Nils Larsen named the body of water for the Norwegian polar explorer Roald Amundsen while exploring this area in February 1929.

North Sea: The North Sea is a marginal sea of the Atlantic Ocean located between Great Britain, Scandinavia, Germany, the Netherlands, Belgium, and France.  An epeiric (or "shelf") sea on the European continental shelf, it connects to the ocean through the English Channel in the south and the Norwegian Sea in the north.  It is more than 970 km long and 580 km wide, with an area of around 570000 km2 .

Børge Ousland: Børge Ousland (born 31 May 1965) is a Norwegian polar explorer, photographer and writer.  He started his career as a Norwegian Navy Special Forces Officer with Marinejegerkommandoen, and he also spent several years working as a deep sea diver for the oil industry in the North Sea.  In 1994, he made the first solo and unsupported journey to the North Pole from cape Arktichevsky in Russia.  As of 2016, that feat has never been successfully repeated.  He made the first unassisted Antarctic solo crossing, between 15 November 1996 and 17 January 1997.  The ski journey was made with kite assistance and also holds the record for the fastest unsupported journey to the South Pole taking just 34 days.  On 22 January 2006, together with Mike Horn he began a journey to the North Pole in full Arctic night, successfully concluded on 23 March.

Norwegian Sea: The Norwegian Sea (Norwegian: "Norskehavet" ) is a marginal sea in the North Atlantic Ocean, northwest of Norway.  It is located between the North Sea (i.e. north of the United Kingdom) and the Greenland Sea and adjoins the North Atlantic Ocean to the west and the Barents Sea to the northeast.  In the southwest, it is separated from the Atlantic Ocean by a submarine ridge running between Iceland and the Faroe Islands.  To the North, the Jan Mayen Ridge separates it from the Greenland Sea.

Mike deGruy: Mike deGruy (December 29, 1951 – February 4, 2012) was an American documentary filmmaker specialising in underwater cinematography.  His credits include "Life in the Freezer", "Trials of Life", "The Blue Planet" and "Pacific Abyss".  He was also known for his storytelling, most notably, a passionate TED talk about his love of the ocean on the Mission Blue Voyage.  His company, Film Crew Inc., specialized in underwater cinematography, filming for BBC, PBS, National Geographic, and The Discovery Channel.  His notable accomplishments include diving beneath thermal vents in both the Atlantic Ocean and Pacific Ocean.  He was a member of many deep sea expeditions and was a part of the team that first filmed the vampire squid and the nautilus.  He was also part of the Deepsea Challenge, where James Cameron went to the bottom of the Mariana Trench.  In 2016, production began on a feature-film documentary about his life and work titled Diving Deep.  The documentary is planned for release in 2017.  Additionally, Mike was well-known for his shark attack on April 2, 1978 by a grey reef shark, and was severely bitten on his lower right forearm, from which he bore scars.

Supporting paragraphs: Børge Ousland North Sea
Answer: journey to the North Pole