The Greenland shark, Somniosus microcephalus, also known as the sleeper shark, gurry shark, ground shark, grey shark, or by the Inuit languages name Eqalussuaq, is a large shark native to the waters of the North Atlantic Ocean around Greenland and Iceland. These sharks live farther north than any other shark species. They are closely related to the Pacific sleeper shark. This is one of the largest species of shark, of dimensions comparable to those of the great white shark. Large Greenland sharks grow to 6.4 metres (21 ft) and 1,000 kilograms (2,200 lb), and possibly up to 7.3 metres (24 ft) and more than 1,400 kilograms (3,100 lb). However, most Greenland sharks observed have been around 3–4.8 metres (9.8–15.7 ft) long and weigh up to 400 kilograms (880 lb). It rivals the Pacific sleeper shark (possibly up to 7 m or 23 ft long) as the largest species in the family Somniosidae. There are no reliable data on their life span, but fully grown Greenland sharks have been recaptured 16 years after being tagged.

Greenland (Kalaallisut: Kalaallit Nunaat, "Land of the Kalaallit";Danish: Grønland) is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe (specifically Norway and later Denmark) for more than a millennium. Greenland is, by area, the world's largest island. With a population of 56,615 (January 2011 estimate) it is the least densely populated dependency or country in the world.

Greenland has been inhabited, though not continuously, by Arctic peoples via Canada for 4500–5000 years. In the 10th century, Norsemen settled on the uninhabited southern part of Greenland. In the 13th century, the Inuit arrived, and in the late 15th century the Norse colonies were abandoned. In the early 18th century, contact between Scandinavia and Greenland was re-established and Denmark established rule over Greenland.

Jonathan Bird's Blue World is an educational television program about the underwater world. The show is hosted by underwater cinematographer Jonathan Bird. This series airs on PBS stations in the US. The program is designed for family viewing, and each segment finds Bird trying to unravel a mystery, witness an animal behavior or explore an underwater environment. The first season consisted of 5 half-hour programs filmed in standard definition, and the second season contained 7 half-hour programs shot in high-definition. The second season won four New England Emmy Awards. The pilot episode from season 1 won a CINE Golden Eagle Award. Season three consists of 9 half-hour programs in HD and will be released August 29, 2011. The program is magazine format with each television episode consisting of 2-3 segments. These segments appear individually on the Blue World website as webisodes.

Episode 1: Blue Shark Adventure, Underwater Cavern, Giants of the Depths

Episode 2: Swimming with Jaws, The Bandana Game, The Shark and the Whale