ST. MARIES - There was thunder on the St. Joe River Saturday, and it had nothing to do with the weather.
Sleek, high-performance jet boats zoomed up and down the St. Joe, banking curves, leaving high-arcing plumes of water behind them as they delighted hundreds of fans who gathered along the banks to watch the first leg of the 2012 Toyota Weaver Seed World Jet River Marathon.
At 1-minute intervals, the boats took off one at a time, supersonic-sounding engines propelling them to speeds of up to 120 mph, leaving smiles lingering on the faces of race fans of all ages as they passed by.
"I wish I had one," said Troy Oliver, 6, of St. Maries.
Troy was at the river with his dad, Joe, and his younger brother, Logan, 5, for the first and second of four 25-mile timed race segments on the river between Calder Bridge and Idaho Forest Industries Landing in St. Maries.
Oliver said the boys woke up early Saturday morning, excited about the event.
Several feet away, a gray-haired man grinned as he watched one of the boats whiz by.
"I want one," he said longingly.
It's the first time jet boat races have been held on the St. Joe.
The world marathon is being hosted on four different Idaho rivers through next Saturday.
On Monday, it moves to Lewiston and the Snake River, then on to the Clearwater in Orofino and then finishes next weekend on the Salmon River in Riggins.
Jet boat race teams from Canada, New Zealand, Mexico and the United States are competing in this year's world marathon.
Riggins resident Kim Friend the U.S.A. World Race Organizer, said the fastest time in the second 25-mile race segment of the day was 16 minutes.
"That won't be the fastest. It will probably be 14 or 15 minutes," Friend said.
The marathon will cover 500 river miles throughout the week with the final leg taking place in Riggins.
Down in Riggins, they've been hosting local jet boat races for 28 years.
Bob Crump, the mayor of Riggins and the official flagger at the finish line in St. Maries, said the jet boat races are his community's biggest annual event.
Crump said it's great for the local economy, and he knows St. Maries will have the same experience.
St. Maries Chamber of Commerce member Annie Frederick said they have been preparing for the races since last fall. Dozens of volunteers have pitched in to help make it happen.
Because it's their first time hosting an event like this, Frederick said organizers were unsure how many people to expect.
"We've had huge support from the community," Frederick said. "I believe that after the weekend, we'll see it will prove it was worth it."
Brett Morton of Coeur d'Alene pulled off St. Joe River Road, parked his vehicle and got out to watch the 1 p.m. race segment from Scott Park, about 14 miles east of St. Maries, at a bend near the middle of the 25-mile race course.
"I think this is a great thing to bring to St. Maries. It's a great way to bring a lot of people and revenue to a small town," Morton said. "It's a lot of fun, and it's free."
There is no charge to watch the races from the river banks.
The final timed races on the St. Joe take place today at 10 a.m. from Idaho Forest Industries Landing to Calder Bridge, and then from Calder Bridge back down to St. Maries at 11:30 a.m.
The World Jet Boat Races will not return to the United States for four years. It rotates through three other participating countries - Canada, New Zealand and Mexico.