A soda geyser is a physical reaction between a carbonated beverage, usually  Diet Coke, and Mentos mints that causes the beverage to be expelled from its container. The candies catalyze the release of gas from the beverage, which creates an eruption that pushes most of the liquid up and out of the bottle. Lee Marek and "Mareks Kid Scientists" were the first to publicly demonstrate the experiment on the Late Show with David Letterman in 1999. Steve Spanglers televised demonstration of the eruption in 2005 became popular on YouTube, launching a chain of several other Diet Coke and Mentos experiment viral videos. Experiments carried out at altitudes ranging from below sea level in Death Valley to the summit of Pikes Peak have demonstrated that the reaction works better at higher elevations.