The Wright Valley, named for Sir Charles Wright, is the central one of the three large Dry Valleys in the Transantarctic Mountains, located west of McMurdo Sound at approximately (77°10′S161°50′E). Wright Valley contains the Onyx River, the largest river in Antarctica, Lake Brownworth, the origin of Onyx River, and Lake Vanda, which is fed by the Onyx River. Its southwestern branch, South Fork, is the location of Don Juan Pond.