Snorkeling in the Florida Keys is considered very safe, provided you follow standard maritime safety protocols and respect the natural environment. The 125-mile island chain houses the only living coral barrier reef in the continental U.S., and the waters are generally calm, shallow, and clear. To ensure safety, the "Blue Star" program recognizes tour operators who follow responsible and sustainable practices. Swimmers are required to use a "divers-down" flag and are encouraged to wear flotation vests, even if they are strong swimmers, to help with visibility to boaters. While marine life like barracudas, nurse sharks, and rays are common, they are generally non-aggressive toward humans unless provoked. The most common "dangers" are actually sunburn, dehydration, and accidentally touching stinging coral or sea urchins, which is why "reef-safe" sunscreen and a "look but don't touch" policy are the golden rules for a safe trip in the Keys.