Cody Garland told ABC affiliate WEAR that the teens were enticed to jump in the water and swim with the gentle giant.
Another teen, MicKayla Burke, said on Twitter that she took a ride, too.
Burke said the ride gave them an adrenaline rush.
That was an adrenaline rush for sure pic.twitter.com/qEhjNe5mgT— mickayla burke (@MickaylllaB) May 8, 2015
But marine life experts warn others not to copy-cat the teens' swim for the sake of the animals.
"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 told ABC News when a different video of a teen riding a whale shark went viral.
But one of the teens in this group commented on WEAR's story to defend the teens' actions, saying they meant the animal no harm.
"There are more important things to worry about than some kids living a once in a life time experience," wrote Cole Wyatt. "We respected the giant and left it alone after getting a couple of pictures and videos with it."