Trinity Island or Île de la Trinité or Isla Trinidad is an island 24 km (15 mi) long and 10 km (6 mi) wide in the northern part of the Palmer Archipelago, Antarctica. It lies 37 km (23 mi) east of Hoseason Island, 72.6 km (45 mi) south of Deception Island in the South Shetland Islands, and 10.3 km (6 mi) north-northwest of Cape Andreas on the Antarctic Peninsula. 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. He was an American sealer, exploring southwards from Cape Horn in his little sloop searching for seal rookeries. The whole archipelago was named in his honour in 1897 by Adrien de Gerlache, leader of the Belgian Antarctic Expedition.

Trinity Island is one of the most northerly of the islands of the Palmer Archipelago, a chain of more than fifty islands running parallel with the coast of the Antarctic Peninsula. It is about 24 km (15 mi) long and 10 km (6 mi) wide, with an irregular shape and coastline that encompasses many points, capes, bays, coves, and other subordinate features. Many of these geographic features have been charted and named by various Antarctic expeditions, as well as the nations of Argentina and Bulgaria.

Trinity Island is separated from Tower Island to the east by Gilbert Strait. Both islands are separated from the Davis Coast to the south by Orléans Strait, running northeast–southwest. To the southwest, Chayka Passage separates Trinity Island from Spert Island by just 110 m (360 ft).

Cape Wollaston marks the island's northwest extremity. The name was originally applied by the 1828-1831 British Chanticleer expedition for William H. Wollaston, commissioner of the Royal Society from 1818–28. 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. Both features were named for Bulgarian fishing trawlers from the Ocean Fisheries company. Continuing east, Cape Neumayer forms the northeast end of Trinity Island. It was charted by the SAE and named after German geophysicist Georg B. von Neumayer.

On the west coast, Preker Point sits 2.1 km (1.3 mi) to the southwest of Cape Wollaston. It is named for a mountain in the Balkan Mountains. It marks the northern point of Saldobisa Cove, which is 2.3 km (1.4 mi) wide, and was named for an ancient Thracian settlement in northern Bulgaria. Burya Point, formed by an offshoot of Ketripor Hill, divides Saldobisa from Olusha Cove to the south. It was named for Burya, a village in Bulgaria. Olusha Cove, named for a Bulgarian fishing trawler, is 2.7 km (1.7 mi) wide and marked to the south by Consecuencia Point.

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.

Towards the southern end of the west coast is Krivina Bay, a 5 km (3.1 mi)-wide bay that indents the coast to a depth of 3 km (1.9 mi). Three small, rocky islands lie in the northern part of the bay. Northernmost is Imelin Island, 600 m (2,000 ft) long by 380 m (1,250 ft) wide. Dink Island lies 120 m (390 ft) to the south. It is 610 m (2,000 ft) long by 320 m (1,050 ft) wide, and lies 180 m (590 ft) north of Rogulyat Island, which is the southernmost of the three. Rogulyat Island is 350 m (1,150 ft) long by 160 m (520 ft) wide. The bay and its islands are named for locations in Bulgaria: the villages of Dink, Krivina, and Rogulyat, and Imelin Cave.