Personal Best is your personal maximum apnea time. Please keep in mind that maximum attempts are not harmless. That’s why training should not be underestimated and is better done in pairs.
When you want to compete with others, select “Ranking” from settings. Your results will be stored online and the ranking is displayed. You need a Google Play Id.
Keep in mind that time measurement is a point of honour. Breathing in is measured as – well – breath. Breathing out is measured as apnea time. That’s why you should try to extend exhaul as long as possible to extend your apnea time.