Professional athletes will be allowed to wear wetsuits in water temperatures up to and including 71.5F/21.9C. Age group athletes will be allowed to wear wetsuits in water temperatures up to and including 76.1F/24.5C.
Originally from: http://www.ironman.com/triathlon/news/articles/2015/02/standardized-global-competition-rules.aspx#ixzz3pv414W3l
國際 Ironman 一般選手只要水溫 24.5 C含以下就可穿防寒衣
Each age group participant shall be permitted to wear a wetsuit without penalty in any event sanctioned by USA Triathlon up to and including a water temperature of 78 degrees Fahrenheit. When the water temperature is greater than 78 degrees, but less than 84 degrees Fahrenheit, age group participants may wear a wet suit at their own discretion, provided however that participants who wear a wet suit within this temperature range shall not be eligible for prizes or awards.