The movie starts out when Johnny Kapahala is living in Hawaii. Johnny has good friends, a great family, and a grandpa who is a surf legend. But then, his dad gets a job transfer and makes his wife and Johnny move to Vermont.
In Johnny's new town, there are two schools: one is a private school where the students are all skiers, and the other is the public school where all the students are snowboarders. Although Johnny goes to the skiers' school, he would prefer to snowboard because he thinks it is more like surfing. Although he has a hard time at first, Johnny eventually learns how to snowboard with some help from Sam Sterlin
While at his new school, Johnny meets a girl named Emily, with whom he becomes good friends. However, a skier named Brett likes Emily as well. During one incident in the mountain, the Urchins (the students from the public school) decide to ride the side of the mountain that belongs to the skiers and are confronted by the Skies (the private school students).
A quick fight ensues between Johnny and Brett, but is immediately dispersed when a snow ranger arrives. When Johnny arrives home after a meeting with his parents and the principal concerning the fight with Brett, Sam tells Johnny that he is moving to Iceland, as are his father's orders since he is a sergeant major in the U.S. Marine Corps. Intent on doing something to prevent the move, Johnny and Sam fly to Hawaii on a cargo plane to stay with Johnny's grandfather.
Johnny and Sam have a great time in Hawaii surfing and enjoying the warm weather, but they decide to come back to Vermont along with Johnny's grandfather, the famous Johnny Tsunami. Johnny, to his amazement, finds out that his grandfather has great snowboarding ability and they decide to ride the skiers' side of the mountain, where the best rides are.
Brett and his gang meet Johnny and his grandfather and they decide to have a one-race challenge between Brett and Johnny. If Johnny wins the race, then the skiers must share the mountain with the snowboarders. If Brett wins, then he is awarded the Tsunami Medal, a prize given to the best surfer in Hawaii. Johnny goes on to defeat Brett, allowing him and Emily to begin a relationship.
The two brothers who own the opposite sides of the mountain finally reveal their story. Their parents couldn't agree on what should happen when they inherited the mountain, which ended up being split between the two families. Johnny wins the race even though Brett played some dirty tricks throughout the race. Johnny's parents decides to throw a celebration party, the brothers finally re-unite and the ending scene shows Johnny and Emily dancing together
- Cary-Hiroyuki Tagawa as Johnny Tsunami
- Brandon Baker as Johnny Kapahala
- Mary Page Keller as Melanie
- Yuji Okumoto as Pete
- Lee Thompson Young as Sam Sterling
- Cylk Cozart as Sgt. Sterling
- Kirsten Storms as Emily
- Zachary Bostrom as Brett
- Gregory Itzin as Headmaster Pritchard
- Taylor Moore as Jake
- Anthony DiFranco as Eddie
- Steve Van Wormer as Randy
- Noah Bastian as Aaron
- Gabriel Luque as Matt
- Anne Sward as Miss Arthur
- The Way (song) - Fastball
- Fire Escape (song) - Fastball
- Rolled - Jeffries Fan Club
- Crystal 52 - Jeffries Fan Club
- Life Jacket - Simon Says