36,000-plus people were killed by the explosion and its effects (Keep in mind that the affected area was much less populated than it is now; the death figures, if the explosion were to happen today, could easily surpass the 2004 Tsunami's figures). The natives on the island and nearby were done in by the blast wave, others were burned alive but hot ash, while most were killed in a series of tsunamis which reached as far as South Africa while odd wave partners as far away as England were reported.
The sky around the world turned a blood red. It is even believed that the famous The Scream art piece depicts this event as was the inspiration of doom for the artist Edvard Munch. A short period of global cooling, volcanic winter, was also recorded.
The change in climate affected crops and the socio-political structure as well. During the period right after Krakatoa there was a noticeable increase in anti-colonial actives by Indonesians and Indians, both of whom feel on hard times due to crop failures.
What is left of Krakatoa's volcano is still active today. A new island, Anak Krakatau, is on the rise.
For more information on the explosion and its effects read the book Krakatoa: The Day the World Exploded: August 27, 1883.
Krakatoa is a prime example of how chaotic nature can be. It is important to remember that while humans are the most constant force on earth, we are not the most powerful.