The island was named by Otto Nordenskiöld, leader of the 1901-1904 Swedish Antarctic Expedition (SAE) in commemoration of Edward Bransfield's "Trinity Land" of 1820.

Trinity Island, or the adjoining Davis Coast stretch of the Antarctic Peninsula, may have been the first part of Antarctica spotted by Nathaniel Palmer, on 16 November 1820.

[5] To the east along the north coast is Lorna Cove, 1.1 km (0.68 mi) wide, with ice-covered Albatros Point marking its eastern shore.

[11] Olusha Cove, named for a Bulgarian fishing trawler, is 2.7 km (1.7 mi) wide and marked to the south by Consecuencia Point.

[12][13] Continuing south down the west coast, just north of Lyon Peak, sits Milburn Bay, fed by Pastra Glacier.

The bay was shown on an Argentine government chart of 1952 and named by the UK Antarctic Place-Names Committee (UKAPC) in 1960 for M. R. Milburn, an air traffic control officer of the Falkland Islands and Dependencies Aerial Survey Expedition (FIDASE), which photographed this area in the period 1955–57.

[18] The bay and its islands are named for locations in Bulgaria: the villages of Dink,[17] Krivina,[15] and Rogulyat,[18] and Imelin Cave.

First shown on an Argentine government chart of 1950, UKAPC named it in 1960 after Judas Iscariot because the rock marks the southern extremity of a hazardous shoal area which extends northward from it for 3 nautical miles (6 km) in an otherwise clear passage.

[25] Cape Wollaston, at the northwest extremity of the island, has been designated an Important Bird Area (IBA) by BirdLife International because it supports a large breeding colony of about 10,000 pairs of southern fulmars.

It has an elevation of about 250 m.[26] A 45-hectare (110-acre) site comprising a rocky headland rising to 250 metres (820 ft) above sea level, at the south-western extremity of the island, has also been designated an IBA because it supports a breeding colony of about 200 pairs of Antarctic shags.