Mason Inlet is an ice-filled inlet which recedes 15 nautical miles (28 km) southwest between Cape Mackintosh

Cape Mackintosh

Cape Mackintosh is a low, ice-covered cape forming the north tip of Kemp Peninsula and the east entrance point to Mason Inlet, on the east coast of Palmer Land. Probably first seen by members of the United States Antarctic Service who photographed a portion of Kemp Peninsula while exploring this...

 and the coastline south of Cape Herdman

Cape Herdman

Cape Herdman is a broad ice-covered cape forming the south entrance point to Violante Inlet, on the Black Coast, Palmer Land. The cape was photographed from the air in 1940 by United States Antarctic Service ; rephotographed from the air in 1947 by Ronne Antarctic Research Expedition and, in...

, along the east coast of Palmer Land

Palmer Land

Palmer Land is that portion of the Antarctic Peninsula which lies south of a line joining Cape Jeremy and Cape Agassiz. This application of Palmer Land is consistent with the 1964 agreement between US-ACAN and UK-APC, in which the name Antarctic Peninsula was approved for the major peninsula of...

. First seen and photographed from the air in December 1940 by members of the United States Antarctic Service (USAS). During 1947 the inlet was photographed from the air by the Ronne Antarctic Research Expedition

Ronne Antarctic Research Expedition

The Ronne Antarctic Research Expedition was an expedition from 1947-1948 which researched the area surrounding the head of the Weddell Sea in Antarctica.-Background:...

 (RARE), who in conjunction with the Falkland Islands Dependencies Survey (FIDS) charted it from the ground. Named by the FIDS for D.P. Mason, their surveyor on the joint British-American sledge journey during the charting of this coast in 1947.