Florida Teen Rides on the Back of a Whale Shark [VIDEO]

Florida native Chris Kreis, 19, was fishing in the Gulf of Mexico when a whale shark the size of the 30-foot boat he was in swam up alongside him and his friend.

Not one to miss out on an opportunity, the teen dove in and grabbed onto the world's largest fish's fin upon the recommendation of his friend, much to the animal's apparent displeasure.

"When I started holding on I felt the whale shark, it started moving itself, it felt the drag and it didn't really want me on there so I let go and that's it," Kreis told NBC2.

In all, Kreis rode for about 20 seconds before he decided he should probably let go. Meanwhile, his friend took a video they later posted on YouTube.

And while whale sharks may be considered the gentle giants of the ocean, Kreis said he spotted two bull sharks, the most aggressive and dangerous kind of shark, swimming in the area, prompting him to swim back to the boat "really quickly."

Whale sharks are not an endangered or protected species; however, while Kreis broke no laws in riding it, marine biologist Bruce Neill argues it wasn't really a good idea.

"When people spend a lot of time and pressure on a fish it takes away a slime that covers the fish," NBC2 reports him as saying. "They need that layer to stay healthy."

Furthermore, while the fish only feeds on plankton, Neill warns that "because they are so very large, they could inflict some harm inadvertently."

Kreis said he didn't realize the health impact he could have had and, should the opportunity arise again, he would approach it differently.

"I would jump in if I saw one again, but next time I wouldn't touch the fish" Kreis said.

In all, scientists estimate that the fish Kreis rode weighed some 50,000 pounds.