The island is located in the Sunda strait between Java and Sumatera. Further to the west there is a string of small volcanic islands, active and inactive. The Krakatau complex comprises of three dead volcanic islands left over from previous volcanoes and the active Anak Krakatau volcano, growing in the middle of the caldera formed by the big blast of 1883. North of this complex are the extinct Sebesi and the older Sebuku island.
Just like its neighbours Sanghiang island is also a volcanic island, formed of a submarine volcanic activity, probably about 800000 - 1.5 million years ago. This was shown by the basalt pillow lava, breccia and other volcanic rocks found in the island and in the nearby Merak area in the mainland. After the volcanic activities died out about 200000 years ago, corals and other marine invertebrate life began to take over and as a consequence the eastern part of the island is now covered with stacks of coral limestones and the beaches are formed of white carbonate sands.
Just as the 780 hectare of the island is covered with lush vegetation, the underwater around the island is also covered with lush marine invertebrate life. Both hard and soft corals cover the gentle slope, and they in turn are covered with algaes.
Saturday 2nd of July, joining a Kapal Selam Diving Club trip, I had another chance to witness this myriad of underwater life. This was my second diving trip to the island. The first one was a fuzzy and blurry memory since it was done only a week after I obtained the open water (beginner diver) certification. I was still a novice then and was still more concerned about how to survive the dive than to actually enjoy the spectacle of the marine life. This time I was a lot more experienced and was even carrying a camera to capture underwater pictures.
That morning we, a group of 15 people of which 10 would dive, sailed for about 1 hour to the island using a wooden boat from Paku Pier in the mainland. Our first dive site was Batu Mandi, south of the island. The sea was very calm, the sky was blue with not even a speck of cloud and the sun shone brightly. We dropped our equipments into the sea and put them on in the water. Then we went in.
The water was greenish and there were lots of particles in it, so visibility was not great. I think it reached about 8 meters at the best. I dropped down to 24 meters. The reef was sloping gently to a white sandy bottom. It was covered with lush coral growth, both hard and soft, interspersed with various sponges, sea squirts, the nasty hydrozoas, feather stars and some sea fans. Little damselfish and anthias swam in and out of table corals. They shared places with some squirrelfish. There were several anemones with Clark's anemonefish (Amphiprion clarkii) living in them. These little cousins of Nemo were my favourite photo objects. Some of them could be quite vicious; they tried to attack my camera.
I was not in the best mood to take pictures that day - which was quite surprising. Usually I'm quite keen on underwater photo hunting. But lately I have been a bit disappointed because I can never get as good pictures as I want. Especially those macro pictures. The night before Jerry and Tom who are two of the very experienced amateur underwater photographers that I know, gave me a few tricks and tips to get good pictures. But after trying several shots I gave up. It's just too difficult for me at that time.
We saw several nudibranches of the family Phyllidiidae, a flatworm, some sea stars, including cushion stars (Culcita novaguineae & Choriaster granulatus) and a seashell of Cypraea sp. The highlight of the dive was a yellow nudibranch with big black dots, which I could not identify. I tried to take pictures of it but failed to get any decent ones. The rather murky sea did not encourage me to try harder, so I switched to taking snapshots of the other divers. Just at the end of the dive Mia pointed out a huge grey moray with two cleaner fish swimming around it. Then we surfaced after a 65 minutes of dive.
Back on the boat my stomach was grumbling wildly and I needed to go to the loo very soon. Luckily it was decided to have the lunch in the island. As soon as the boat touched the old wooden pier I jumped out and went inland looking for a secluded grove under a thick bush which could pass as an emergency loo. After the business was over I joined the others sitting on the white sandy beach enjoying a boxed nasi Padang lunch. Then some of us joked and talked while the other snoozed a bit.
At around 1 pm we went back to the boat and sailed to our next dive site Tanjung Bajo which is located in the north of the island. The water was a bit wavy by then and I had to drank a few gulps of water while putting on my gear in the choppy sea. Then we went down.
visibility was a bit better, up to around 10 meters, but there was a medium current. Still buddying with Teres I went down to around 22 meters and then drifted along the reef. Here the reef growth was also quite good. The gentle slope was covered by both hard and soft corals. I identified some Acropora, Montipora, Fungia simplex, and Echinopora hard corals. They were interspersed with Lobophyton, Sarcophyton, sea fan, whip coral, organ pipe coral, Dendronepthya and Xenia sp soft corals.
There were more fish here than at the first site. There were the usual damselfish, anthias and squirrelfish. There's a school of small fusiliers, and a bunch of butterflyfish and batfish. I saw two anemones with some false clown anemonefish (Amphiprion ocellaris) residents. I got a shot of a giant clam (Tridacna squamosa), a pair of yellow christmas tree worm and of a Chromodoris sp nudibranch, which I was happy about. But my best shot that day was of a hairy nudibranch Flabellina rubrolineata. This was definitely the best dive of the two we did that day, as we also saw a green turtle (Chelonia mydas) gracefully swimming running away from us.
At the end of the dive just before surfacing we saw two crown-of-thorns (Acanthaster sp.), a type of sea stars which is notoriously infamous as coral killers. Indeed the corals around those two animals looked bleached and dead. Some divers think that we should kill every crown-of-thorn that we see, to prevent it from out breaking and destroying all the corals in the area. Some others think that we should leave it to the nature. However there are a lot of cases where these animals do bloom out of control with devastating consequences to the coral life.
Some researches show that the blooming was caused by human interference in removing their predators. Some other researchers seem to think that the outbreaks are caused by the excessive amount of agricultural run-off. In any case, when there is an outbreak of growth of crown-of-thorns, human interference is needed to clean it up and prevent more coral destruction. Where there have not been uncontrolled outbreaks we should make sure that there are predators around which could help preventing an outbreak. According to an article about Acanthaster planci in a marine biology site the predators of the crown-of-thorns are a type of Annelida called Pherecardia striata or fire worms, harlequin shrimp (Hymenocera picta), a crab from the genus Trapezia, a type of mollusk called the giant triton Charonia tritonis, and some fish variety such as napoleon wrasse, triggerfish and pufferfish.
The dive ended the trip that day. After 66 minutes we surfaced and sailed back to the mainland, ending the day by frolicking in the pool, drinking some vodka and enjoying the sunset in Oka's villa in Anyer.