Each year, approximately 250 children under the age of five drown in swimming pools. In fact, it is the second leading cause of accidental death among children in this age group. Many parents and caregivers think they'll hear a child in distress, but the tragic truth is drowning happens quickly and without warning. Adult supervision is the most important protection against accidental drowning, but two thirds of toddler drowning incidents happen when parental supervision fails and there's no backup system in place. In order to prevent toddler drowning, you must think in terms of layers of protection.