Simplify the following text for a Grade 10 native English-speaking person.
Original: Yellowstone Lake is one of the largest high-altitude lakes in North America and is centered over the Yellowstone Caldera , the largest supervolcano on the continent .
Simplified: Yellowstone is the site of a huge ancient volcano , whose remains are called the Yellowstone Caldera . The caldera is the largest volcanic system in North America .