The eruption of Mount Krakatoa in 1883 was one of the most violent volcanic events ever recorded. A huge explosion (equivalent to 150 megatons of TNT) occurred as seawater came in contact with hot magma and turned instantly to steam. The blast was heard over 4,000 km away in Australia and India. The Volcano Explosivity Index (VEI) of the eruption was 6 (colossal).
The whole volcano was destroyed because of the massive explosion. Parts of the volcano fell into the sea and caused a giant tsunami (40 meters). The dust from the eruption reached the stratosphere and affected weather worldwide for several years. More than 35,000 people were killed by the tsunami and eruption. Only about a third of the pre-1883 island population survived the blast.
From 1927 to 1930, there were several underwater eruptions on the site of the old Krakatoa volcano. On August 11, 1930, a new volcano and island appeared. This new volcano and island are called "Anak Krakatau" (Child of Krakatoa).
The island of Anak Krakatoa is a national park. To land on the island, tourists must obtain a permit from Balai Konservasi Sumber Daya Alam (BKSDA).
From Anyer and Carita
The easiest way to get in to Krakatoa is by contacting tour operators in Anyer or Carita. Anyer can be reached from Jakarta with public bus from Kalideres bus station. The range of the tour fee will be around Rp 750,000 - 3,000,0000 depend on how many people join in the tour group and also the length of the tour. The price will include food, boat, tent and guide.
One foreign photographer/volcano guide in Jakarta presumably arranges monthly trips to Krakatau trough Carita. He arranged our tour, and can be contacted on firstname.lastname@example.org, or you can contact lagunatrip.com; they can arrange a trip with a local price.
Another option for traveling from Jakarta, you can hop on a silver min van (Angkutan) from Carita to Cilegon (around 1.5 ~ 2 hours) at RP 20,000. The driver will drop you off at a junction where you can take a VIP bus (around 3 hours) back to Jakarta. The VIP bus is air-conditioned and direct to Jakarta. The cost is about RP 17,000 one way.
The other way to reach Krakatau, which is less famous for the foreigners but has become a better choice for the locals who want to save some money, is through Lampung Province. It takes more time to reach Krakatau from here but the journey is worth it if you want a more adventurous way. Lampung can be reached by land or ferry from Merak Port. The ferry journey takes 2 hours to Rajabasa Port in Lampung. The cost is Rp 10,000. From Rajabasa bus station, you can take a yellow minibus to Kalianda for around Rp 12,000. You can contact Krakatoa Nirvana Resort (62-727-322888, 322 900) who occasionally arrange trips to Krakatau. The tour cost is Rp 3,500,000 for the whole boat, including lunch and a tour guide. If you have ten people with you, it is better to get your trip from here.
The cheaper option is to get a boat at Canti Port. You can reach Canti Port from Kalianda with motorcycle taxi (Ojeg) for Rp 10,000 or minibus for Rp 5,000. If you want to hire a traditional fishing boat to take you to Krakatoa, you can make a deal with the boat owner there. One day boat rental will cost you around Rp 1,500,000 (day time only). You have to bring your own life vest because the traditional fishing boat will not provide it. There is a cheaper option from Sabesi Island. Regular boats from Canti Port operate from 11:00 AM to 2:00 PM and cost Rp 15,000. If you are in the rush to Sabesi, you can hire a boat for only Rp 400,000 one way. In Sabesi Island, you can contact some fishermen there who will hire their boat. The price for the boat will be around Rp 300,000 for day time and Rp 600,000 for night time. You have to bring your own food and life vest. One of the rangers (Pak Akhyar, mobile:+6281369281861) on this island can arrange a convenient trip to Krakatau. The price will include boat, food, tend and a tour guide. He also provides the life vest. You can negotiate the price with him directly.
Beware of strong current and large waves during August, September, October and November. Anak Krakatau is an active volcano.
Most of the tour operators in Labuan and Anyer have a camp during the night at Rakata Island. You can enjoy the eruption of Krakatoa at night from here. If you want to stay in Sabesi island, you can stay at a simple hotel which belongs to the Indonesia Tourism Board, just walking distance from Sabesi island jetty. The contact person is Pak Hayun, mobile +628187013757. The price is reasonable between Rp 200,000- Rp 300,000 per room which can accommodate 10 people in one room. The private room is little bit more expensive with TV inside but the size is smaller. The private room can only accommodate 4 people. Some people in this island also provide homestay for the travelers. The price is negotiable. If you are adventurous enough, you can try this option.
Anuk Krakatua is an active volcano. Do not visit the volcano if it is erupting.