Extreme sports are nontraditional sports and activities that require participants to combine athletic skill with pronounced risk. 
An extreme sport is a popular term for certain activities which have a high level of danger. These activities often involve speed, height, a high level of physical training. We can call many kinds of sports extreme ones. Extreme sports are rarely sanctioned by schools. 
Usually athletes don't have a coach or may hire him later. People in extreme sports complete not only against each other, but also against weather and difficulties and conditions of exact kind of extreme sport.
There are many extreme sports that take place in air, land, and water. For example there are some of them: ski jumping, sky diving ,sky surfing, sky flying, indoor climbing, BMX (bicycle motocross), mountain biking, mountain boarding, skateboarding, snowboarding, powerboat racing, surfing, whitewater kayaking, windsurfing. All these sports need to have special equipment and glasses. 
For surfing we need a surfboard and swimming kits. For snowboarding we need a snowboard and special boots to fix them on the board and a suit and also sunglasses that help to look at the snow and a helmet. For BMX sport you need a special not high bike with small wheels. Sportsmen can dress fashionably, usually in shorts and a T-shirt,trainers, if they want they wear a cap.
We can be sure that many new extreme sports will appear soon. Every year more and more people are interested in extreme sports and take active part in them. I'm sure that soon extreme sports will be on a high level