Tremors is a hybrid steel roller coaster located at Silverwood Theme Park in Athol, Idaho. The ride opened in 1999.
The initial ride concept was developed by park owner and founder, Gary Norton, after the success of the park's first wooden coaster, Timber Terror. The design was finalized by Custom Coasters International, and the ride was constructed in-house by the park.
The ride features a loose theme of earthquakes. This theme was later extended to the nearby Aftershock roller coaster when it opened in 2008.
Tremors features four underground tunnels, which gave it the record of most times underground on a roller coaster's layout from 1999 to 2006, when The Voyage opened at Holiday World with 5 underground tunnels.
In 2010, the ride was the first to receive Topper Track, a new track system designed by Rocky Mountain Construction (RMC) of Hayden, Idaho. The track, which consists of several layers of wood topped with steel, is designed to cut down on track maintenance and daily wear and tear. RMC's founder, Fred Grubb, had previously assisted with the initial construction of the ride as Silverwood's construction manager.
Starting in 2021, Tremors was also the first coaster to receive RMC's new 208 ReTraK, which is steel track that completely replaces old wood track. In 2025, the last of the ride's wooden track was removed in favor of steel 208 ReTraK. As such, it is no longer considered a wooden coaster.