Barrow itself has several tourist attractions that support just over 1,000 jobs; the town saw a higher growth in tourist expenditure during the 2000s than Cumbria as a whole and had about 2.3 million overnight stays during 2008. Barrow's most popular free-entry tourist attraction is the Dock Museum. The museum tells the history of Barrow (including the steelworks industry, the shipyard and the Barrow Blitz), as well as offering gallery space to local artists and schoolchildren. It is built upon and around an old graving dock. Walney Island has two world-renowned nature reserves (the 130 hectare (0.5 sq mi) South Walney Nature Reserve and the 650 hectare (2.5 sq mi) North Walney Nature Reserve). Both nature reserves have Site of Special Scientific Interest designation, as do the Duddon Estuary and Sandscale Haws to the north of the borough. Barrow has a number of beaches which are popular in the summer with sunbathers, kitesurfers and caravanners. They include Earnse Bay, Biggar Bank, Roanhead and Rampside. The first two of these provide views of the Isle of Man and Anglesey on exceptionally clear days. The wider borough has more than 60 km of coastline. The Park Leisure Centre is a fitness suite with a pool, set in the Barrow Park. The historic ruins of Furness Abbey and Piel Castle, which are both managed by English Heritage, are also popular tourist destinations. South Lakes Safari Zoo is one of Europe's leading conservation zoos and has been voted Cumbria's best tourist attraction in five non-consecutive years although it has a checkered history; it lies within the borough of Barrow-in-Furness on the outskirts of Dalton. The zoo underwent a multi-million pound expansion during the mid-2010s. It now holds thousands of animals and covers an area of making it one of the Northern England's largest such parks.