The sound made by the Krakatoa volcanic eruption on August 27, 1883, was so loud it ruptured eardrums of people 40 miles away, travelled around the world four times, and was clearly heard 3,000 miles away.

It was heard 1,300 miles away in the Andaman and Nicobar islands (“extraordinary sounds were heard, as of guns firing”); 2,000 miles away in New Guinea and Western Australia (“a series of loud reports, resembling those of artillery in a north-westerly direction”); and even 3,000 miles away in the Indian Ocean island of Rodrigues, near Mauritius* (“coming from the eastward, like the distant roar of heavy guns.”¹) In all, it was heard by people in over 50 different geographical locations, together spanning an area covering a thirteenth of the globe.

The  volcano erupted with a force so great that it tore the island apart, emitting a plume of smoke that reached 17 miles into the atmosphere, according to a geologist who witnessed it.

The explosion created a deadly tsunami with waves over a hundred feet (30 meters) in height. One hundred sixty-five coastal villages and settlements were swept away and entirely destroyed. In all, the Dutch (the colonial rulers of Indonesia at the time) estimated the death toll at 36,417, while other estimates exceed 120,000^.

The British ship Norham Castle was 40 miles from Krakatoa at the time of the explosion. The ship’s captain wrote in his log, “So violent are the explosions that the ear-drums of over half my crew have been shattered. My last thoughts are with my dear wife. I am convinced that the Day of Judgement has come.”

Source: Nautilus http://nautil.us/blog/the-sound-so-loud-that-it-circled-the-earth-four-times