BOO! at the Zoo presented by U.S. Cellular® is Knoxville’s largest Halloween event featuring several nights of not-too-scary Halloween fun perfect for preschool and elementary-aged children. A Halloween tradition for 32 years, BOO! at the Zoo is a family event featuring trick-or-treating along the BOO! Trail, where little trick-or-treaters can fill their bag with goodies as they make their way through the zoo. Each night of BOO! at the Zoo will have a variety of entertainment.