Tremors is a roller coaster at Silverwood Theme Park in Athol, Idaho, that opened on May 15, 1999. Built by Custom Coasters International as a wooden twister, it became famous for a first drop that plunges into an underground tunnel before crashing back above ground through the floor and ceiling of one of the park’s gift shops.
The ride’s four underground tunnels gave it the record for the most underground passages on a roller coaster layout from 1999 until 2006, when The Voyage at Holiday World opened with five. Over time Tremors has been steadily modernized, moving from its original wooden track to steel track systems while keeping its signature layout and tunnels intact.
Stats at a Glance
- Park: Silverwood Theme Park, Athol, Idaho
- Manufacturer: Custom Coasters International (built 1999); retracked to steel by Rocky Mountain Construction (2010–2025)
- Opened: May 15, 1999
- Height: About 85 ft
- Top speed: About 50 mph
- Length: About 3,158 ft
- Inversions: 0
The Ride Experience
Tremors runs as a twisting, sit-down coaster with a duration of about one minute and 40 seconds. Its defining moment comes early: the first drop sends riders underground through one of four tunnels built into the ride’s terrain, an effect that made it a standout attraction when it opened in 1999.
Trains navigate a mix of drops, turns, and tunnel passes across roughly 3,158 feet of track, reaching about 50 mph and pulling around 2.5 G’s along the way, all without a single inversion.
From Wood to Steel
Tremors began as an all-wood coaster from Custom Coasters International. In 2010 it became the first coaster fitted with Rocky Mountain Construction’s Topper Track to reduce maintenance, and starting in 2021 RMC gradually replaced the remaining wooden structure with its 208 ReTraK steel track system, a conversion completed for the 2025 season along with new Millennium Flyer-style trains.
Explore more: Explore more roller coasters.
Tremors FAQs
Is Tremors a wooden or steel roller coaster?
Tremors opened in 1999 as a wooden coaster but was fully converted to steel track through Rocky Mountain Construction’s Topper Track and 208 ReTraK systems, completing the transition by 2025.
How many underground tunnels does Tremors have?
Tremors has four underground tunnels, a feature that held the record for most underground passages on a coaster from 1999 to 2006.
How fast does Tremors go?
Tremors reaches speeds of about 50 mph during its roughly 100-second ride.
Get More from Tremors
Log the coasters, stadiums, and venues you’ve experienced, rate Tremors, and see what your friends thought. Get the ThrillZing app.
Photo: Matthew Nelson from Hayden, United States / CC BY 2.0, via Wikimedia Commons.