Swimming in a recreational lake on April 23, 2011 in Glades County, Florida, was epidemiologically implicated as the source of an outbreak of Norovirus. A point source of exposure was likely. The reported symptoms, incubation, and duration of illness were consistent with Norovirus. Two people reported having gastrointestinal symptoms within 2 weeks prior to visiting the campground. Even though they felt well, it seemed likely that they could have shed virus into the lake water. There had been a report of someone having diarrhea prior to swimming. The person who was laboratory confirmed to be infected with Norovirus swam in the lake on April 22 and April 23.