Small undersea volcanoes can generate unexpectedly large tsunamis through rapid caldera collapse, as demonstrated by the 2022 Hunga eruption in Tonga that produced a 40-meter tsunami. Researchers studying the eruption found that a 4-kilometer-wide caldera sank about a kilometer, potentially amplifying the tsunami's destructive power. Scientists warn that submarine volcanic hazards remain poorly understood due to the difficulty of accessing deep-ocean eruption sites.