While the exact definition and what is included as extreme sport is debatable, some attempted to make classification for extreme sports. In 2004, author Joe Tomlinson classified extreme sports into those that take place in air, land, and water,^[9]

Nine air sports are mentioned including: BASE jumping, bungee jumping, gliding, hang gliding, high wire, ski jumping, sky diving, sky surfing, and sky flying.

twenty land sports which include: adventure racing, aggressive inline skating, BMX, caving, motocross, extreme skiing, freestyle skiing, land and ice yachting, mountain biking, mountain boarding, outdoor climbing, sandboarding, skateboarding, snowboarding, snowmobiling, speed biking, speed skiing, scootering and street luge.

Fifteen water sports including: barefoot water skiing, cliff diving, free-diving, jet skiing, open water swimming, powerboat racing, round the world yacht racing, scuba diving, snorkeling, speed sailing, surfing, wakeboarding, whitewater kayaking, windsurfing, and kitesurfing.