Gulf of Ob

The Gulf of Ob (also known as "Ob Bay") (, "Obskaya guba") is a bay of the Arctic Ocean, located in Northern Russia at the mouth of the Ob River. It is the world's longest estuary.
Geography.
The mouth of the Gulf of Ob is in the Kara Sea between the Gyda and Yamal peninsulas. It is about long and varies in width from about . It generally runs north and south. The gulf is relatively shallow, with an average depth from , which restricts heavy sea transport. The Taz Estuary is an eastern side-branch formed by the Taz River.
There are several islands near the mouth of the Ob, at the beginning of the estuary, such as Khaley Island. All these islands are close to the shore and they are generally flat and low-lying. They are protected wetlands under Ramsar. Further north, except for a few islands located close to the shore, such as Khalevigo and Nyavigo, the Gulf of Ob is free of islands until it meets the Kara Sea.
Beluga whales seasonally migrate to the Gulf of Ob.
Hydrocarbons.
Very large natural gas and petroleum deposits have been discovered in this region. Oil and gas from the wells are sent South via pipeline and rail transport. The Yamburg gas field is the world's third largest natural gas field, and is located between the southern portion of the gulf and the Taz Estuary to the east. A new port is being developed at Sabetta, on the west bank of the gulf.