Of the seven East Frisian islands, Norderney is the youngest. The island has only existed in its present form since the middle of the 16th century, being the eastern remnant of the larger island Buise. The larger island of Buise was split into two parts during the Grote Mandrenke flood of 1362, the eastern half at first being called Ostrende. What was left of Buise shrunk in size over the years and finally disappeared into the North Sea during the St. Peter's Flood of 1651. Ostrende, on the other hand, grew in size, and is noted in a 1550 census as "Norder neys Oog" (Northern New Island), and having a church and 18 houses. The inhabitants at this time worked principally as fishermen. In the second half of the 18th century the sea trade industry grew in importance. Next to fishing, tourism became important to the island economy. In 1797, Norderney became the first German resort on the North Sea.