A surf break (also break, shore break, or big wave break) is a permanent (or semi permanent) obstruction such as a coral reef, rock, shoal, or headland that causes a wave to break, forming a barreling wave or other wave that can be surfed, before it eventually collapses. The topography of the seabed determines the shape of the wave and type of break. Since shoals can change size and location, affecting the break, it takes commitment and skill to find good breaks. Some surf breaks are quite dangerous, since the surfer can collide with a reef or rocks below the water. Surf breaks may be defended vehemently by surfers, as human activities and constructions can have unintended and unpredictable consequences which can be either positive, negative, or unknown. In 2008, surfers and environmentalists opposed a toll road project in Orange County, California that would have changed sediment patterns and affected the world-class Trestles surf break north of San Onofre State Beach which attracted 400,000 surfers in 2007.In 2007, the NSW Geographical Names Register began formally recognizing names of surf breaks in Australia, defining a surf break as a ""permanent obstruction such as a reef, headland, bombora, rock or sandbar, which causes waves to break"".One of the largest surf breaks in the world is the Jaws surf break in Maui, Hawaii, with waves that reach a maximum height of 40–60 feet (12–18 m).