JOAN JANOWSKI, far left, will lead a free geocaching tour while exploring the Kennebec Estuary 9:30 a.m. to 11:30 a.m. Saturday, July 20. Meet at the Whiskeag Trail kiosk at the Bath YMCA to practice using Global Positioning System receivers to hide and seek containers known as geocaches or caches. Register at 442-8400 or bkolak@kennebecestuary.org.