It begins with the Guia Narrows (Angostura Guía) and is located in Magallanes y Antártica Chilena Region.
The kawésqar people sailed its waters from around 6,000 years ago until end of 20th century, as they inhabited its coasts.
The channel is named after Pedro Sarmiento de Gamboa, who was a Spanish explorer who navigated the region's waterways between 1579 and 1580.
During the first 65 nautical miles, it runs in a general south-southeasterly direction, and is flanked by Chile mainland on the east and Esperanza, Vancouver and Piazzi islands on the west.
Then it turns abruptly eastward for about 4 nmi, where the channel's name changes to Farquhar Pass.