The small volcanic island of Pulau Weh lies northwest of Sumatra in Indonesia, where the Indian Ocean meets the Andaman Sea. Nature and wildlife are diverse both above and below the waves. Pierre Constant recounts his revisit to Sumatra.
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On my previous trip to Sumatra, the diving had been stimulating, but I had got a bit carried away with the time underwater on one particular dive. The boat returned to the village of Iboih on Pulau Weh, and I disembarked on the black sandy beach with my equipment and underwater camera. Half an hour later, I was back in my room when I suddenly felt dizzy and was seized with intense vertigo. The walls started dancing in all directions. I crashed onto the bed, nauseous and with a bad headache. Mentally, I could not control the pain and knew straight away that I was in serious trouble.
My friend ran downstairs to the dive centre and requested oxygen at once. Forty-five minutes later, my condition had not improved. Fully aware that I was affected by decompression illness, my concern grew. As I was covered by DAN insurance, I called a hyperbaric physician in the Philippines. “No big deal,” he said. “You just suffer from dehydration!”
The nearest decompression chamber in Sabang was not operational, as one had recently blown up in Java, killing five people inside after one of the patients had stupidly lit a cigarette in the chamber. Hard to believe, but true.
In the morning, I was taken to the hospital in Sabang, where I received treatment for five hours. The treatment was repeated the next day for three hours, but there was still no improvement. In less than two weeks, I was supposed to start a high-altitude trek in the Karakoram mountain range in northern Pakistan. Would I be fit to do so in my condition? I had no clue.
Sure enough, when I got to the Karakoram, I experienced vertigo at 3,000m as I hiked for a good three hours on a narrow trail against a cliff above a precipice. I had to keep my eyes fixed on the ground as I could not look over the edge, or I would have plummeted to my fateful end. A very challenging trek it was. There was no way I was going to make it above 5,200m. I was too unwell to climb Manglik Sar, which rises to 6,000m. But I digress…
Forces shaping the landscape
Back to Indonesia… Humanity will never forget the Indian Ocean earthquake and tsunami that struck Banda Aceh and the west coast of Sumatra 20 years ago on 26 December 2004 at 8 a.m. Known as the Sumatra-Andaman earthquake, with an epicentre off the west coast of North Sumatra, it reached a magnitude of 9.3 on the Richter scale.
The undersea megathrust was caused by a rupture along the fault between the Burma and Indian Plates. It is well known that there is a subduction zone in the Sunda Trench between the Indian Plate (part of the Indo-Australian Plate) and the Burma Plate (a minor microplate), where the former subducts (plunges) under the latter. Seen as an extension of the Eurasian Plate, the Burma Plate comprises the Andaman and Nicobar Islands and a portion of northwestern Sumatra. A large extension of the boundary between the Burma Plate and the Indian Plate slipped, causing a megathrust over 1,600km. The fault type changes from subduction to “strike-slip”, where two plates slide past one another in opposite directions.
The boundary underwent thrust faulting, with the Burma Plate shifting up 5m vertically and 11m horizontally over the Indian Plate. The rapid rise of the seafloor over seven minutes generated a massive tsunami, with waves up to 30m high, killing around 229,800 people in 14 countries along the coasts of the Indian Ocean.
Banda Aceh reported the greatest number of deaths, at 61,000 (25 percent of the population). It was the most powerful earthquake of the 21st century and the third most powerful earthquake ever recorded in the world. The hypocentre of the main earthquake was north of Simeulue Island, 160km off the western coast of Sumatra in the Indian Ocean, at a depth of 30km below mean sea level.
The only two greater megathrust earthquakes in human history were the 1960 Valdivia earthquake (9.5) in Chile and the 1964 Alaska earthquake in Prince William Sound. As a reminder, the volcanic activity resulting from the Indo-Australian Plate subducting the Eurasian Plate is responsible for the creation of the Sunda Arc, the volcanic island chain of Indonesia, i.e., the Sunda Islands.
During the last glacial maximum, 18,000 to 20,000 years ago, Sundaland was one large landmass uniting the Asian mainland, including the Malay Peninsula, Borneo, Bali, Java and Sumatra. The so-called “land bridge” allowed animals to move freely from Southeast Asia to the nearby islands of today. Sea depths over the Sunda Shelf rarely exceed 50m. This Sunda landmass was separated from the Sahul landmass—further south and east—by the Wallace Line. It isolated Sulawesi, the Lesser Sunda Islands and Australia/New Guinea, which had different flora and fauna—that of the Australasian realm. Sea level rise during the meltwater pulse 14,600 to 14,300 years ago changed the landscape dramatically. Pleistocene paleo-river systems of the Sunda Shelf were submerged by present-day sea levels.
Human migration
Having left Africa 1.8 million years ago for its long migration, the early human species Homo erectus took advantage of the sea level regression during the last ice age and the existence of a land bridge across the Sunda Shelf to reach Java in the early Lower Pleistocene.
Gayo Highlands. The Leuser Mountain Plateau lies in the southeast of Banda Aceh in the highlands of North Sumatra. Archaeological research has revealed prehistoric occupation by two distinct human races around 5,000 BP: the Australomelanesoid and the Mongoloid.
Around 7,400 years ago, a group of Australomelanesoids inhabited the eastern coast of Sumatra. Associated with a migration of the Hoa Binh culture from northern Vietnam, they hunted and fished, exploiting marine biota such as molluscs and snails. Stone tools such as pebble axes, round adzes and pick-adzes have been found. Artefacts found include tusks used for necklaces (as beads) and remains of bowls made of plaited rattan.
The Loyang Ujung Karang cave near Takengon also revealed occupation by another group around 5,080 (±120) BP associated with an Austronesian migration from South China to Thailand throughout the western part of Sumatra. Red slip pottery similar to that found at the Ban Chiang archaeological site in Thailand was discovered. At Loyang Ujung Karang, oval-shaped burials were excavated, showing flexed burials with funeral gifts such as arrows, plaited rattan and decorated pottery fragments. The Austronesian migration brought along Lapita pottery. These prehistoric finds support the identity of a Gayo culture, separate from the province of Aceh.
The Gayo Highlands are renowned for a very unique speciality: coffee. In the days of the Dutch colonial empire, coffee was a delicacy reserved only for white colonists; none of the locals were allowed to drink it.
But there’s a twist. Have you ever seen the movie The Bucket List, starring Jack Nicholson and Morgan Freeman? In the film, the two ageing friends venture on a special world tour of the “must-do” experiences before they die. At one point, Nicholson’s character introduces his friend to “kopi luwak”, explaining that the indigenous people had discovered that not only did white men like coffee, but so did the cute animal known as the Asian palm civet or musang (Paradoxurus hermaphroditus).
For some reason, this creature loves to eat coffee berries, and the beans are then excreted in its faeces after a fermentation process as they pass through the guts of the mammal. The locals discovered this method of making coffee for their own consumption! This is “kopi luwak”. The irony is that nowadays, the Gayo people sell this unique brew to tourists at a high price, around US$10 per cup! Sweet revenge for the old days.
Nias Island. On the western coast of Sumatra, the culture of Nias Island (Tanö Niha) is rather unique. Austromelanesoid occupation dates back to 12,000 years ago through migration from mainland Asia. It was once assumed that the Nias people were descended from the Hoa Binh people of Vietnam. Recent genetic research shows that the ancestors of the Nias people came from Taiwanese aborigines via the Philippines 4,000 to 5,000 years ago. Megaliths and stone carvings found in the interior of the island prove that the ancient Nias people practised megalithic culture. Nias is the largest island in Sumatra—an archipelago of 131 islands—with an area of 5,121km2.
Vowing to return
A cheeky, inquisitive journalist once asked a multimillionaire: “Sir, how did you get so rich?” With a serious look, the man humbly replied, “I failed eighteen times.” The moral of the story resonated with me. One should never give up. Ever since my episode of decompression illness on my last visit to Pulau Weh, I had been haunted by a feeling of “unfinished business” in Sumatra and the need to overcome those nasty memories… with some creative achievement.
Eight years had elapsed since my last visit. I had not forgotten the terrible ordeal I had experienced in 2016. A lesson learned, indeed, but I had to rise above failure and be reborn like the phoenix.
Getting there
A slow passenger car ferry was scheduled to leave the port of Ulee Lheue in Banda Aceh at 8 a.m., for the 1.75-hour crossing to Pulau Weh. It was already crowded as I boarded, dragging my two pieces of luggage on wheels. I was the only foreigner on board. During the ferry ride, the Indian Ocean was as flat as an oil slick.
Yandi, the taxi driver, expected my arrival in Balohan and transferred me to Iboih on the western side of Pria Laot Bay. It was a 45-minute drive along a winding road over a hilly landscape covered in lush jungle. The village itself was more of a commercial centre. But the location was a haven for Indonesian and Malaysian Chinese tourists, judging by the impressive number of orange life jackets hanging in front of shops everywhere.
Snorkelling activities for tourists drew a substantial income for the locals. Nonetheless, 13 dive shops were also found in Iboih. It was Friday morning, a Muslim prayer day, so the dive centre did not open until 2 p.m. Not to worry, as I was not planning to dive until tomorrow. It felt super quiet with no foreign visitors. The gentle waves crashed softly on the coral beach below the guesthouse. It was hot and humid, close to 32°C.
A dive guide’s remarkable resilience
Shortly before 9 a.m., I met my dive guide, a young man who was all smiles, with an open, welcoming face and lively eyes. He was a joyful fellow despite the fact that, as a teenager he had lost his family in the December 2004 tsunami.
Today, he is married and has a family of his own. He is a dive instructor and loves the ocean. The past has been a trampoline for his future. He is a survivor.
Diving
Iboih faces a couple of islands to the east and northeast: Pulau Rubiah and Pulau Seulako. Some rock clusters jut out of the water to the south and north of Seulako. Most of the dive sites are only five minutes away by speedboat. Conditions looked perfect, and the water temperature was a balmy 30°C. My dive guide had donned his wetsuit, with even a hood attached. I was happy with just my shorts!
Arus Balee. The first dive was at Arus Balee, which means “wild current”. We jumped in on the western side of some volcanic rocks emerging from the water. The current came from the southwest. Heading south, then east around the bend, the visibility was optimal.
At 30m, large golden gorgonian sea fans decorated the slope. Several bushes of dark green Tubastrea hard corals hosted a swarm of orange scalefin anthias (Pseudanthias squamipinnis). Clouds of small blue triggerfish dotted the blue space, with occasional curtains of black pyramid butterflyfish (Hemitaurichthys zoster).
A little school of yellowfin or golden banded goatfish (Mulloidichthys vanicolensis) hovered near a boulder and mixed with goldspot or emperor seabream (Gnathodentex aureolineatus). White collared or redtail butterflyfish (Chaetodon collare), Meyer’s butterflyfish (Chaetodon meyeri) and lined butterflyfish (Chaetodon lineolatus) were common. The powder-blue surgeonfish (Acanthurus leucosternon) was conspicuous. Golden yellow with blue lips, the three-spot angelfish (Apolemichthys trimaculatus) was ravishing.
Limbo Gapang. “Could you take me on a macro dive?” I enquired. Not a problem. Limbo Gapang in Pria Laot Bay was not what I had expected. This underwater mountain had a flat top covered in coral with patches of sand. I encountered a few Indian fish species, such as the Indian Ocean mimic surgeonfish (Acanthurus tristis); the Indian humbug (Dascyllus carneus), which was white with a black stripe and a black dorsal crest; the Randall’s fusilier (Pterocaesio randalli); the Indian sailfin tang (Zebrasoma desjardinii) and the Andaman butterflyfish (Chaetodon andamanensis). The dive guide pointed out a Glossodoris atromarginata nudibranch, which was white with a black girdle.
A quest for breakfast
It was still dark outside when I woke up at 5:30 a.m. the next day. It had been raining. I waited until 7 a.m. to look for a place to have breakfast in Arus Balee. Nothing opens in Iboih before 8 a.m.
At a street stall, I got an Indonesian dish of rice, rice noodles, vegetables and two cold boiled eggs with some “sambal” red sauce for IDR 15,000 (~US$.90/EU€.87). Nearby, at the Qibo Qibo coffee shop, two elderly women provided me with hot tea for IDR 6,000 (~US$.36/EU€.34). A bit further on, the simple stall of 72-year-old Halima sold doughnuts for IDR 3,000 each (~US$.18/EU€.17). I was all set!
More diving
Batee Tokong, north of Seulako Island, is probably the fishiest dive in Pulau Weh due to an ever-present current. The site got its name, meaning “temple rock”, from the shape of the outcrops.
We submerged on the protected left side, rounding the drop-off to the north. Swirling into the blue was a large school of bigeye jacks (Caranx sexfasciatus). I invited myself into their timeless farandole, and they wrapped themselves around me like cotton wool. On the eastern side, a school of ringtail surgeonfish (Acanthurus auranticavus), all black with a white ring around the caudal peduncle, moved like a hunting pack.
Seulako Cave. Located to the west of Arus Balee and Seulako Island, the dive starts with a slope and no current. A hawksbill sea turtle roamed about while two devil rays (Mobula tarapacana) cruised by in the blue. It was a scene of graceful nature, but the rays were hard to get to. White with a pattern of dark marks, a honeycomb moray (Gymnothorax favagineus) peeped innocently out of a hole. The so-called cave was an overhang at a depth of 16m, with some sleek unicornfish, a couple of bannerfish, an attractive coral grouper and a cool star puffer (Arothron stellatus) resting on the floor.
Canyon. North of Zero Point, the northern tip of Pulau Weh, this dive site was at the far end of Sumatra. On the western side was an area of calm waters. “We should expect some current,” warned the dive guide. But today, there was none!
Big round boulders made up the slope as we headed in a northwest direction. I could not see much of a canyon at first, but the guide later informed me that it started at the 50m mark with two parallel walls. Above, in the 35m zone, the wall was full of gorgonians and green Tubastrea coral, with swarms of orange scalefin anthias. There was a school of sleek unicornfish and a large inquisitive dogtooth tuna (Gymnosarda unicolor) zoomed by.
The dive guide led me down to a rock arch, where he slipped through for a photo. A cushion star (Culcita novaeguineae) had taken shelter under it. A small school of yellow saddle goatfish (Parupeneus cyclostomus) with yellow-phase juveniles attracted my attention. Apart from the clouds of small blue triggerfish, there was little fish life.
Seulako Drift, on the east side of Seulako Island, has a slight current. A few oriental sweetlips (Plectorhinchus vittatus) hovered near a boulder, an Indian Ocean mimic surgeonfish beckoned and a yellow teardrop butterflyfish (Chaetodon interruptus), with its black tear mark, was a wonder! The dive guide spotted a beautiful critter I had never seen before: a Dermatobranchus ornatus nudibranch, which had no gills, was greenish in colour, with pink flat warts on its back, and two black rhinophores.
Some orange-brown sponges, with pink cup corals attached, appeared towards the end of the dive. I was captivated by an anemone hosting some skunk anemonefish and forgot about the time. Once at the safety stop, my computer displayed a 25-minute deco stop! Thank heaven, the dive guide was next to me to hand me his octopus. Otherwise, I would have ended up in the new hyperbaric chamber at Sabang Hospital! A serious warning to over-excited photographers.
There was some variation in the condition of the reefs between dive sites, such as Arus Balee and Seulako, Seulako and Batee Tokong, etc. Avoid Pulau Rubiah, which is a haven for snorkellers. Heavy tourist traffic has led to some damage to the reef.
Hot Springs. One special site that stood out was Hot Springs. In Pria Laot Bay, south of Gapang, the salt-and-pepper, silty-sand seafloor has been the stage for the remnants of ancient volcanic activity: sulphur hot springs. Streams of bubbles rise like beads from the sediment or from some active vents, gurgling effusively.
The site attracts several fish species, including juvenile blue-lined snappers (Lutjanus kasmira) and the pale grey Indian puffer (Arothron immaculatus). A must-do experience. Upon surfacing, we were greeted by a tropical rainshower, which made the dive guide burst into laughter like a happy child.
Topside excursions
Diving aside, no trip to Sumatra would be complete without a little inland exploration. Markedly mountainous and covered in jungle, the northwestern tip of the island (also known as the province of Aceh) has the second most important population of orangutans in the world, after Borneo.
With a population of around 14,700 individuals (as of March 2016), the Sumatran orangutan (Pongo abelii) is a distinct species endemic to northern Sumatra. It differs from the Bornean orangutan (Pongo pygmaeus) in that it is thinner and has a longer face and longer, pale red hair. Males grow to about 1.70m tall and 90kg, while females average 90cm and 45kg.
Compared to its Bornean cousin, the Sumatran orangutan tends to be more frugivorous and insectivorous, with a liking for durians, lychees, figs and jackfruit, but also includes bird eggs and small vertebrates in its diet. It has been known to use tools, such as twigs or sticks, to dig into tree holes for termites or to poke into a bee’s nest to feast on the honey. The Sumatran orangutan is mostly arboreal due to large predators on the ground, such as the Sumatran tiger and Sunda clouded leopard.
A baby orangutan is cared for by its mother for eight years. At 8 years of age, a female is considered fully matured and begins to have offspring. A male orangutan reaches adulthood at 13 to 15 years of age. It has a fully grown beard, long hair and developed cheek callosities. Having attained sexual and social maturity, he now only travels alone. In the wild, males live 47 to 58 years, while females live only 44 to 53 years.
Orangutan sanctuaries
The main threat to Sumatran orangutans is logging and conversion of forests to agricultural land or palm oil plantations. The two best locations where orangutans are likely to be seen are Bukit Lawang Reserve, 90km northwest of Medan, and Gunung Leuser National Park, a sanctuary set up by a Swiss organisation in the 1970s to rehabilitate orangutans rescued from the logging industry. Rangers are trained to teach orangutans vital jungle skills, and the rehabilitation programme has been deemed a success.
The species has been listed as Critically Endangered on the IUCN Red List since 2000. Protection of the forest habitat against deforestation and hunting was determined to be a more cost-efficient way of maintaining wild orangutan populations. A timeframe of 10 to 20 years is expected in WWF for Nature’s efforts to stop the clearing of a large part of the natural forest near Bukit Tigapuluh National Park. Sumatra currently has the highest rate of deforestation in the world.
In 2017, a new species, the Tapanuli orangutan (Pongo tapanuliensis), was described as a distinct species south of Lake Toba—an isolated population of 800 individuals (2018) found in the hilly region of the Batang Toru area of South Tapanuli. The species holotype was a complete skeleton of a large male killed by locals in 2013. The skull and teeth differed significantly from those of the other two orangutan species.
Genetic evidence shows that the Tapanuli orangutan diverged from the Sumatran orangutan 3.4 million years ago—a speciation that was later accelerated by the volcanic eruption around 75,000 years ago at the site of present-day Lake Toba in Sumatra. Tapanuli orangutans have frizzier hair, smaller heads and flatter and wider faces. Dominant males have a prominent moustache, large flat cheek pads and larger upper canines.
Exclusively arboreal, their diet of caterpillars and conifer cones is also unique. They live in tropical and subtropical broadleaf forests at elevations between 300m and 1,300m, spread over an area of about 1,000km2, and their predators are the Sumatran tiger and the Sunda clouded leopard.
Final thoughts
In Sumatra, the people were generally very friendly and helpful, with individuals who inspire, such as those I met on my travels, embodying a life-affirming resilience in the wake of the tsunami devastation. The scenery and wildlife in the natural areas above and below the waves were beautiful and diverse, and there was a rich cultural, geological and prehistoric heritage to explore. However, as a nature lover and a person who respects the environment, I observed some disconcerting behaviours, including the common practice of littering wherever and whenever and the compulsive habit of chain smoking. Alas, this was normal and acceptable in the areas I visited.
Keen to experience something new on this trip, I ended up in the Banyak Islands off the northwestern coast of Sumatra. There was no diving here, but sea crocodiles were lurking around. ■
Sources: wikipedia.org, fishbase.org, marinespecies.org
