Lake Martha is a lake in Kings Canyon National Park

Kings Canyon National Park

Kings Canyon National Park is a National Park in the southern Sierra Nevada, east of Fresno, California. The park was established in 1940 and covers...

, on the Le Conte Divide, 1 miles (1.6 km) north of Mount Reinstein and 1.2 miles (1.9 km) southwest of Mount Goddard

Mount Goddard

Mount Goddard is a mountain of California's Sierra Nevada, in the north section of Kings Canyon National Park. Goddard forms the southwest boundary of the Evolution Basin....

. Lake Martha is notable for being the source of the San Joaquin River

San Joaquin River

The San Joaquin River is the largest river of Central California in the United States. At over long, the river starts in the high Sierra Nevada, and flows through a rich agricultural region known as the San Joaquin Valley before reaching Suisun Bay, San Francisco Bay, and the Pacific Ocean...

. It is also on the easiest route to Hell for Sure Pass. Due to its elevation, it can be completely frozen at high summer (August).