That impressive eruption is coming from the relatively small cone that formed after the VEI 6 eruption in 1883. “Anak” means “son.”
See those hills in the background? They are all that remain of Anak’s big daddy – the original Krakatau/Krakatoa volcano. (I think the beach shown also formed from a remnant of the older edifice, as no other islands are that close, but would have to check on that.)
Curious about the Big One there? Read the report of the Krakatoa Committee of the British Society, The eruption of Krakatoa, and subsequent phenomena, from 1888.