Frobisher went on voyages to the Guinea coast of Africa in 1553 and 1554, and during the 1560s he preyed on French shipping in the English Channel under a privateering license from the English crown; he was arrested several times on charges of piracy but never brought to trial.
Having become interested in the possibility of finding a Northwest Passage to the Pacific Ocean, Frobisher in 1576 obtained the command of three small ships, in one of which he succeeded in crossing the Atlantic that year. He reached Labrador and Baffin Island and discovered the bay that now bears his name. He returned to England with reports of possible gold mines, thereby obtaining royal backing for two further expeditions to the same area, in 1577 and 1578. On the latter of these expeditions, Frobisher sailed up Hudson Strait but then turned back to anchor at Frobisher Bay, where his attempts to establish a colony were unsuccessful. Frobisher’s single-minded pursuit of mineral treasure limited the exploratory value of his voyages, and, when the ores he brought back from his third voyage proved to contain neither silver nor gold, his financing collapsed, and he was forced to seek other employment.
In 1585 Frobisher sailed as vice admiral of Sir Francis Drake’s expedition to the West Indies, and three years later he played a prominent part in the campaign against the Spanish Armada, being knighted during the operations. Over the next six years Frobisher commanded various English naval squadrons, including one in the Azores (1591) that unsuccessfully sought to capture Spanish treasure ships. In 1594 he was mortally wounded fighting a Spanish force on the west coast of France. Frobisher was undoubtedly one of the ablest seamen of his time, but as an explorer he lacked the capacity for patient factual investigation.