During his 1553 voyage across the Barents Sea, English explorer Hugh Willoughby thought he saw islands to the north. Based on his description, these islands were subsequently depicted and named "Willoughby's Land" and "Macsinof Island" on maps published by Petrus Plancius in 1592 and 1594. Gerardus Mercator included them on his 1595 map. Willem Barentsz found no sign of Willoughby's discoveries and omitted them from his map published in 1599, but they continued to appear on Arctic maps published by Jan Janssonius and Willem Blaeu at least into the 1640s.