The sailing ships of the VOC needed much repair and maintenance after their arrival in Asia, during their stay in tropical waters and before their return to Europe. The ship was careened to clean and repair the hull. Before Batavia the coast was too shallow to do this work. On 14 kilometer of shore lies a group of coral islands in deep water. The biggest island of 12 hectare was already in 1614 – before the foundation of Batavia – used for the maintenance of the ships. The Dutch called the island Onrust (Restless) because the work continued night and day and never stopped. On Onrust permanent buildings like a forge and workshops were built, and expanded in the course of the 17th century. By the 18th century Onrust, with two sawmills, a big forge, workshops, warehouses, cranes and more than 1000 laborers, was the biggest and most advanced shipyard in Southeast Asia. In 1795 the Dutch demolished the fort and the main part of the buildings on Onrust. In 1800 the British burned down the remaining buildings. Between 1980 and 1995 archaeological research was done on Onrust. Today the island is a protected monument. The historic park with the buildings of the quarantine station, foundation of the VOC fort, graveyard and museum attracts many visitors from Jakarta.