At only 3 1/2, Weston Letter already knew how to swim, and he could almost get up on water skis. "We're water people -- we live in Gilbert, Arizona, where there are lakes and pools everywhere," says his mother, Druann. But one afternoon when she was in the house and his father was in the garage that overlooks the backyard, Weston wandered out to their pool and fell in. He was out of sight for only a few minutes, but by the time his parents found him, it was too late. "My husband is a firefighter and saves lives. I'm a first-grade teacher and a safety freak -- probably one of the most overprotective moms you'll ever meet," says Letter. "But together, we couldn't save our little boy." As parents, we try to do everything humanly possible to protect our kids. Yet, as the Letters learned that day, you can never be too careful around the water. Drowning is the second-leading cause of unintentional deaths for children in this country, just behind motor-vehicle crashes, and more than 700 children drown every year, says Ileana Arias, PhD, director of the Injury Center at the Centers for Disease Control and Prevention. But here's some reassuring news: In a world where danger often seems to lurk everywhere, tragedies in the water are actually something that every one of us can avoid.