Precipitation runoff from the mountain drains into tributaries of Portage Creek and Twentymile River before emptying into Turnagain Arm.

Topographic relief is significant as the summit rises approximately 4,400 feet (1,340 m) above Bear Valley in 1.25 miles (2.01 km).

The mountain's toponym was officially adopted in 1976 by the United States Geological Survey to commemorate Alaska Congressman Nick Begich (1932–1972), who was a member of the U.S. House of Representatives when he disappeared along with House majority leader Hale Boggs and two others on October 16, 1972, during an airplane flight from Anchorage to Juneau.

The Begich, Boggs Visitor Center is located at Portage Lake.

[4] Weather systems coming off the Gulf of Alaska are forced upwards by the Chugach Mountains (orographic lift), causing heavy precipitation in the form of rainfall and snowfall.