Skydiving is a method of transiting from a high point in the atmosphere to the surface of Earth with the aid of gravity, involving the control of speed during the descent using a parachute or parachutes. For human skydiving, it may involve a phase of more or less free-falling (the skydiving segment) which is a period when the parachute has not yet been deployed and the body gradually accelerates to terminal velocity. Read more on Wikipedia
Snorkelling is the practice of swimming on or through a body of water while equipped with a diving mask, a shaped breathing tube called a snorkel, and usually swimfins. In cooler waters, a wetsuit may also be worn. Use of this equipment allows the snorkeler to observe underwater attractions for extended periods with relatively little effort and to breathe while face-down at the surface. Read more on Wikipedia
Hiking is a long, vigorous walk, usually on trails or footpaths in the countryside. Walking for pleasure developed in Europe during the eighteenth century. Religious pilgrimages have existed much longer but they involve walking long distances for a spiritual purpose associated with specific religions. "Hiking" is the preferred term in Canada and the United States; the term "walking" is used in these regions for shorter, particularly urban walks. In the United Kingdom and the Republic of Ireland, the word "walking" describes all forms of walking, whether it is a walk in the park or backpacking in the Alps. The word hiking is also often used in the UK, along with rambling (a slightly old-fashioned term), hillwalking, and fell walking (a term mostly used for hillwalking in northern England). The term bushwalking is endemic to Australia, having been adopted by the Sydney Bush Walkers club in 1927. In New Zealand a long, vigorous walk or hike is called tramping. It is a popular activity with numerous hiking organizations worldwide, and studies suggest that all forms of walking have health benefits. Read more on Wikipedia
Swimming is an individual or team racing sport that requires the use of one's entire body to move through water. The sport takes place in pools or open water (e.g., in a sea or lake). Competitive swimming is one of the most popular Olympic sports, with varied distance events in butterfly, backstroke, breaststroke, freestyle, and individual medley. In addition to these individual events, four swimmers can take part in either a freestyle or medley relay. A medley relay consists of four swimmers who will each swim a different stroke, ordered as backstroke, breaststroke, butterfly and freestyle. Read more on Wikipedia