The huge tsunami ripped through tourist spots and beach resorts, killing hundreds and injuring almost a thousand more
Anak Krakatau, translated as "Child of Krakatoa" is an island located in the Sunda Strait between the two islands of Java and Sumatra.
It was formed after its 'parent volcano' Krakatoa erupted in 1927, with Anak Krakatau breaking water in 1930.
The Sunda Strait connects the Java Sea to the Indian Ocean.
The region is home to many popular tourist destinations that were hit, including the Tanjung Lesung beach resort in the west of Java island.
Why did the volcano cause a tsunami?
When volcanoes erupt, hot magma presses underground and can move and break through colder rock. This can trigger a landslide.
But because the volcano is underwater, the water is pushed as it moves, causing a tsunami on the surface of the sea.
The Anak Krakatau volcano has been active in recent months.
Indonesia's geologic agency said the volcano erupted for two minutes and 12 seconds on Friday, forming an ash cloud 400 metres above the mountain.
It recommended nobody be allowed within two kilometres of the crater.
How many people have died?
At least 222 people have been killed and 843 injured, with this number expected to rise.
Along with tourist beach resorts, deaths have been reported in the Pandegland and Serang on Java, and Lampung province on Sumatra.
Footage of a band playing at a beach was circulated on social media, with its singer confirming the band's bassist and road manager had died, with the other members missing.

Anak Krakatau, translated as "Child of Krakatoa" is an island located in the Sunda Strait between the two islands of Java and Sumatra.
It was formed after its 'parent volcano' Krakatoa erupted in 1927, with Anak Krakatau breaking water in 1930.
The Sunda Strait connects the Java Sea to the Indian Ocean.
The region is home to many popular tourist destinations that were hit, including the Tanjung Lesung beach resort in the west of Java island.

Why did the volcano cause a tsunami?
When volcanoes erupt, hot magma presses underground and can move and break through colder rock. This can trigger a landslide.
But because the volcano is underwater, the water is pushed as it moves, causing a tsunami on the surface of the sea.
The Anak Krakatau volcano has been active in recent months.
Indonesia's geologic agency said the volcano erupted for two minutes and 12 seconds on Friday, forming an ash cloud 400 metres above the mountain.
It recommended nobody be allowed within two kilometres of the crater.
How many people have died?
At least 222 people have been killed and 843 injured, with this number expected to rise.
Along with tourist beach resorts, deaths have been reported in the Pandegland and Serang on Java, and Lampung province on Sumatra.
Footage of a band playing at a beach was circulated on social media, with its singer confirming the band's bassist and road manager had died, with the other members missing.