 De Mafra joined the expedition of Ruy López de Villalobos as pilot of the "San Juan", one of six ships.Thus it is a mystery that many scholars have been trying to solve, when we find him as one of the men of the galleon "San Cristobal" who made it to the port of Mazaua in 1543.The galleon was separated from the fleet during a severe storm as the ships sailed between Eniwetok and Ulithi.