Yves-Joseph de Kerguelen-Trémarec

Yves-Joseph de Kerguelen-Trémarec (13 February 1734 – 3 March 1797) was a Breton explorer and French naval officer.

Early life
He was born in Landudal, Finistère. During the Seven Years' War, Kerguelen-Trémarec was a privateer, but without much success.

Rockall
In 1767 he sailed near Rockall, or Rokol. Although he may not have approached within sight of it, or even within 150 miles, he appears to have had good information regarding it. His charted position for it was only 16 miles North of its actual position and he accurately described its appearance and the nearby Helen's Reef, "East of Rokol, ¼ league away, there is a submerged rock over which the water breaks". Afterwards he published a map of the area in 1771.

Discovery of the Kerguelen Islands
In 1772, he sailed to the Antarctic, in search of the fabled Terra Australis, where he discovered the Kerguelen Islands and took possession of various territories for France. He was accompanied by the naturalist Jean Guillaume Bruguière.

In his report to King Louis XV, he greatly overestimated the value of the Kerguelen Islands; consequently, he was sent off on a second expedition, again reaching Kerguelen. By now, it had become clear that these islands were desolate and quite useless, and certainly not the Terra Australis. On his return, Kerguelen-Trémarec was sent to prison.

During the French Revolution, he was seen as a victim of the Ancien Régime and restored to his position, taking part in the Battle of Groix. He died in 1797 as a Rear Admiral and commander of the port of Brest.