Answer :

The first person to have discovered Ontario was Etienne Brule, a French explorer, who did not fully explore the whole province of Ontario. This was in 1610 to 1612. The second person to have explored it was an English explorer Henry Hudson, who claimed the land as English territory. He sailed into the Hudson Bay (now named after him) in 1611. In 1615, Samuel de Champlain who is noted as founding distinct parts of Canada and the United States sailed into Lake Huron with other French settlers and missionaries who started to set up posts along the Great Lakes.
The French explorer, Etienne Brule discovered Ontario.