ABC News' Matt Gutman and Anthony Castellano report:

A Florida teen didn't hesitate to hitch a ride on a 30-foot-long, 50,000-pound whale shark in the Gulf of Mexico when it swam past his boat.

The whale shark was cruising off the coast of Florida last week when Chris Kreis, 19, and his family spotted the shark in the ocean. But to Kreis, it looked like the world's biggest boogie board. Kreis jumped off the back of a boat and latched onto the dorsal fin.

"I decided, you know what, maybe I should go try and swim with him. I might not be able to do it ever again," Kreis said.

Kreis' joy ride on the fish off Captiva's coast was short-lived and ended after only nine seconds, which was captured on video Saturday.

"He began to descend, and if something doesn't want you on it, you might as well just let it go," he said.

Despite its name, whale sharks are considered the gentle giants of the sea and are about the size of a school bus. They hold the distinction of being the ocean's largest fish and feed mostly on plankton.

Kreis' stunt has led to a boatload of scrutiny by some critics because the human contact can potentially harm whale sharks.

"When people spend a lot of time and a lot of pressure on a fish, it takes away that slime covering and potentially has negative health impacts for the fish," marine biologist Bruce Neill said.

These kinds of interactions between man and sea creature have increased recently, raising questions about how much humans should be allowed to encroach.

William Waterman was arrested in February after police spotted photos he had posted on Facebook holding a manatee in Florida. Hugging, touching or harassing protected manatees is illegal in Florida.

Ana Gloria Garcia Gutierrez was arrested last year after she turned herself in when photos surfaced of her riding a manatee, violating the state's Manatee Sanctuary Act.

Riding whale sharks is not illegal and Kreis says he would do it all over again if given the opportunity.

"I would absolutely swim with another whale shark," he said.

(Image Credit: ABC News)