"Swim-with" activities, in which humans enter the water to interact with wild cetaceans, are a popular form of ecotourism; however, there is considerable disagreement as to whether these encounters constitute a threat to the animals. To evaluate effects of swim-with activities, we observed the behavior of wild bottlenose dolphins near Panama City, FL, where dolphins have regular encounters with tourists. We identified certain dolphin behaviors indicative of habitual interaction with humans, and we classified individual dolphins as "habituated" or "unhabituated" to human interaction based on presence or absence of these behaviors. We identified at least seven habituated dolphins. All habituated dolphins permitted people to swim nearby, and many accepted fish handouts from humans. We identified specific human-dolphin interactions that posed a risk for dolphins or humans, and we calculated that human interaction put a specific juvenile dolphin at risk once every 12 min, including being fed by humans once every 39-59 min. Humans interacting with that dolphin were estimated to be at risk once every 35 min. We concluded that food provisioning was the probable basis for swimming with wild dolphins near Panama City and, therefore, human interaction at this location was likely to be harmful to wild dolphins. We suggest that swimming with wild bottlenose dolphins in U.S. waters may sometimes be based on feeding, to the detriment of the animals involved and in violation of the U.S. Marine Mammal Protection Act.