section_path: Humans and the sea/Leisure
section_name: Leisure
paragraph_text: Leisure
  
  Use of the sea for leisure developed in the nineteenth century, and became a significant industry in the twentieth century. Maritime leisure activities are varied, and include beachgoing, cruising, yachting, powerboat racing and fishing; commercially organized voyages on cruise ships; and trips on smaller vessels for ecotourism such as whale watching and coastal birdwatching.
  
  Sea bathing became the vogue in Europe in the 18th century after William Buchan advocated the practice for health reasons. Surfing is a sport in which a wave is ridden by a surfer, with or without a surfboard. Other marine water sports include kite surfing, where a power kite propels a rider on a board across the water, windsurfing, where the power is provided by a fixed, manoeuvrable sail and water skiing, where a powerboat is used to pull a skier.
  
  Beneath the surface, freediving is necessarily restricted to shallow descents. Pearl divers can dive to 40 feet (12 m) with baskets to collect oysters. Human eyes are not adapted for use underwater but vision can be improved by wearing a diving mask. Other useful equipment includes fins and snorkels, and scuba equipment allows underwater breathing and hence a longer time can be spent beneath the surface. The depths that can be reached by divers and the length of time they can stay underwater is limited by the increase of pressure they experience as they descend and the need to prevent decompression sickness as they return to the surface. Recreational divers restrict themselves to depths of 100 feet (30 m) beyond which the danger of nitrogen narcosis increases. Deeper dives can be made with specialised equipment and training.