See news report here:

http://www.wfaa.com/news/local/Two-boys-in-critical-condition-after-nearly-drowning-on-field-trip-157317515.html

Breath holding games are dangerous and life threatening. Read what just happened in Dallas, Texas. In this case it appears that the lifeguards saved the boys’ lives by responding quickly and performing CPR. 

We strongly recommend banning long breath holding at pools.  Lifeguards should be trained to stop breath holding games and breath holding challenges, such as swimming underwater for distance.  Learn more ...