Andrew Hudson of Winter Springs was swimming Monday with friends in the Little Big Econ State Forest when he kicked what he thought was a log in the water.
The object was actually an alligator nearly 10 feet long. It came up behind Hudson and jerked him underwater.
Hudson told Florida Fish and Wildlife Conservation Commission investigators that he knew there were alligators that swam in the park's river, but he had not seen any before he was attacked.
"It just came up behind me. I didn't see one all day in there and then it just came up behind me and I felt it and I started freaking out and swam as fast as I could," Hudson said.
When he got to shore, blood was running from the top of his head. Hudson wrapped his shorts around his head to stop the bleeding.
His friend Mark O'Shea ran for help to a forestry office about a half-mile away.
"They looked at me like I was crazy. I'm like, 'My friend really got bit by an alligator,'" said O'Shea.
Doctors at a Seminole County hospital treated Hudson with stitches and staples for several puncture wounds on his head.
The wildlife commission will send an alligator trapper to trap and kill the alligator that bit Hudson, agency spokeswoman Joy Hill said Tuesday.