Sayaxché is a municipality in the El Petén department of Guatemala, on the Río La Pasión River. It covers an area of 3,904 square kilometre…Sayaxché is a municipality in the El Petén department of Guatemala, on the Río La Pasión River. It covers an area of 3,904 square kilometres or 1,507 square miles, and had 55,578 inhabitants at the 2002 Census; the latest official estimate was 114,781 inhabitants.