Journey to the Center of the Earth: Glowstick Drop
Professor Anderson leads the group through the underground cave. He almost falls down a deep chasm as he tries to assure the group that he's good with directions. He attempts to use a flare to measure the depth of the chasm, but the magnesium rocks cause it to explode. Hannah then gives him a glowstick, and he uses that to determine that the chasm is about 200 feet deep.