Drew Mandala went for a run near South Pointe Park on Sunday morning when he noticed people looking into the water.
"I came over and there it was. I couldn't believe it," Mandala said.
Mandala was looking at an alligator.
Florida Fish and Wildlife Conservation Commission personnel and Miami Beach police later rescued the gator, which had gotten lost and was struggling.
Alligators are typically found in freshwater.
They can tolerate saltwater for brief periods of time, according to the Smithsonian's National Zoo & Conservation Biology Institute.
The gator was not injured.