After intermittent eruptions at the end of 2021, the Hunga-Tonga-Hunga-Ha'apai volcano became a one-in-1000-years disaster on January 15.
A tsunami hit Tonga after the volcano erupted for eight minutes, throwing clouds of ash into the sky. Entire villages were wiped out by the waves.
Communications went down or were intermittent for those trying to reach loved ones.
Shock waves traversed many thousands of kilometres, were seen from space, and recorded in New Zealand some 2000km away.
Three people were killed, and medical experts said many others showed signs of post-traumatic stress disorder.
"They thought it was World War III," Amanaki Misa, the Pacific Medical Association team leader stationed in Tonga, said in April.
Scientists have been studying the eruption since. NASA said it caused what is likely the highest plume on record, reaching the third layer of the atmosphere.
Tonga is still recovering, and the eruption will be commemorated on its anniversary in the New Year.