Hidden Volcano Abyss: In January 2022, one of the most powerful volcanic eruptions in recorded history rocked the Pacific islands of Tonga, sending shockwaves around the world. Through first-person accounts of the disaster and eyewitness footage, experience the terrifying power of the eruption and the devastating tsunami that struck the shores of Tonga. Why was this eruption so big, how did it cause the tsunami, and could another disaster loom? NOVA investigates on "Hidden Volcano Abyss."