The pirates captured 234 people from the islands and took them on a 27-day voyage to Algiers, where most of them spent the rest of their lives in bondage. One of the captives, Lutheran minister Ólafur Egilsson, managed to return in 1628 and wrote a book about his experience. In 1636, ransom was paid for 34 of the captives, and most of them returned to Iceland. After this, a small fort was built on Skansinn (that is, "the bastion"), and an armed guard was established to keep watch from the mountain Helgafell for the approach of ships. For centuries, the people of the Vestmannaeyjar had a hard struggle for existence, living from fishing and wild birds and their eggs, which they gathered in the cliffs and rock stacks offshore. At the end of the 19th century, when the population was about 600, great changes took place in the lifestyle of the islanders. In 1904, the first motorised boat was purchased, and more followed soon afterwards. By 1930, the population had risen to 3,470. The Vestmannaeyjar have always been at the forefront of developments in fishing and sea food processing, and are the most productive fishing centre in the country. Shortage of fresh water was also a problem for a long time, but a great improvement took place in 1968 when a pipeline was laid. The area is very volcanically active, like the rest of Iceland. There were two major eruptions in the 20th century: the eruption in 1963 that created the new island of Surtsey, and the Eldfell eruption of January 1973, which created a 200-metre-high mountain where a meadow had been, and caused the island's 5,000 inhabitants to be temporarily evacuated to the mainland. In 2000, Heimaey stave church, a replica of the Haltdalen Stave Church containing a replica of the St Olav frontal, was erected at Skansinn as a gift from the Norwegian government to Iceland, commemorating the conversion of Iceland to Christianity a thousand years before. A ferry service from Landeyjahöfn (closer) and sometimes under bad conditions Þorlákshöfn (further away) and flights to /from Vestmannaeyjar Airport connect the largest island with the rest of Iceland, making 5-6 roundtrips per day. Iceland has ordered an electric ferry with a 3MWh battery and capacity for 550 passengers and 75 cars for the 13 km route.