The Arafura Sea is bordered by the Torres Strait and through that the Coral Sea to the east, the Gulf of Carpentaria to the south, the Timor Sea to the west and the Banda and Ceram seas to the northwest. It is 1,290 kilometres (800 mi) long and 560 kilometres (350 mi) wide. The depth of the sea is mainly 50–80 metres (165–260 feet), with the depth increasing to the west.
The sea lies over the Arafura Shelf, part of the Sahul Shelf. When sea levels were low during the last glacial maximum, the Arafura Shelf, the Gulf of Carpentaria and the Torres Strait formed a large flat land bridge connecting Australia and New Guinea and easing migration of humans from Asia into Australia. The combined landmass formed the continent of Sahul.
The International Hydrographic Organization (IHO) defines the Arafura Sea as being one of the waters of the East Indian Archipelago. The IHO defines its limits as follows:
On the North. The Southeastern limit of the Ceram Sea [A line from Karoefa, New Guinea, to the Southeastern extreme of Adi Island, thence to Tg. Borang, the Northern point of Noehoe Tjoet [Kai Besar] (5°17′S 133°09′E / 5°17′S 133°09′E / -5.283; 133.150)] and the Eastern limit of the Banda Sea [From Tg Borang, the Northern point of Noehoe Tjoet, through this island to its Southern point, thence a line to the Northeast point of Fordata, through this island and across to the Northeast point of Larat, Tanimbar Islands (7°06′S 131°55′E / 7°06′S 131°55′E / -7.100; 131.917), down the East coast of Jamdena [Yamdena] Island to its Southern point, thence through Anggarmasa to the North point of Selaroe and through this island to Tg Aro Oesoe its Southern point (8°21′S 130°45′E / 8°21′S 130°45′E / -8.350; 130.750)].
On the East. The Southwest coast of New Guinea from Karoefa (133°27'E) to the entrance to the Bensbak River (141°01'E), and thence a line to the Northwest extreme of York Peninsula, Australia (11°05′S 142°03′E / 11°05′S 142°03′E / -11.083; 142.050).
On the South. By the North coast of Australia from the Northwest extreme of York Peninsula to Cape Don (11°19′S 131°46′E / 11°19′S 131°46′E / -11.317; 131.767).
On the West. A line from Cape Don to Tanjong Aro Oesoe, the Southern point of Selaroe (Tanimbar Islands).