St. Brendan the Navigator was a 6th-century Irish monk known for his legendary sea voyages. He is often credited with exploring the Atlantic Ocean and is said to have discovered various islands, including Saint Brendan's Island, which some believe to be North America. His adventures are detailed in the medieval text "Navigatio Sancti Brendani," which blends history and myth. Brendan founded several monasteries in Ireland and is considered one of the early Christian missionaries. His feast day is celebrated on April 16, and he is the patron saint of sailors and travelers, symbolizing exploration and faith in the unknown.