East Tennessee is filled with a diversity of attractions, recreational areas and annual festivals, making it a popular vacation destination. Home to a number of urban centers, including Chattanooga, Knoxville and Kingsport, East Tennessee never fails to entertain those looking for big-city attractions. Families in particular enjoy the Knoxville Zoo and the Tennessee Aquarium in Chattanooga. Dollywood, a large theme park in Pigeon Forge, attracts visitors to its thrilling rides, annual festivals and constant musical entertainment. Those in search of natural wonders appreciate The Lost Sea, which is considered to be America's largest underground lake. Located in Sweetwater, visitors embark on glass-bottom boat tours that weave through the large, ancient caverns. Roughly half of the world-famous Great Smoky Mountain National Park is found in East Tennessee, with the other half located in North Carolina. With an entrance to the park near Pigeon Forge, this park is a haven for those wishing to hike, horseback ride and camp.