Panajachel is the lake's front door and its agency town: boats to the Kaqchikel villages, the dawn climb up Indian Nose for the light coming over the volcanoes, Volcán San Pedro from the village of the same name, kayaks, and the shuttles that connect Atitlán to Antigua, Xela and Chichicastenango.
The public boats are cheap and frequent and need no agency at all — you turn up at the dock and go. What the operators sell is the things that need a vehicle or a guide: the ridge walks, the volcano, the weaving co-operatives, and the market at Chichicastenango on Thursdays and Sundays.