First in a series of articles on Indonesia by Scuba Diver’s Senior Travel Editor Don Silcock, with this one providing an overview of the expansive country
Photographs by Don Silcock
It is said that if the 16,000-plus islands of the vast Indonesian archipelago did not exist, there would only be 23 hours in our day…
To put that rather bold statement into perspective requires a basic understanding of the Indonesian Throughflow which, at the most fundamental level, is simply the largest volume of moving water in the world.
It is, however, an incredibly complex natural phenomena – the Reader’s Digest version of which is that as the Earth rotates around its polar axis, huge amounts of seawater accumulate in the northwest Pacific Ocean, producing a disparity of some 20mm to 30mm between the seawater levels there and those in the Indian Ocean to the south.
Water always flows from high to low, and that flow through the archipelago from the Pacific to the Indian Ocean is the Indonesian Throughflow.
And those thousands of islands spread out across the archipelago act as a kind of hydraulic brake on the Earth’s rotation, so that it takes 24 hours for one complete rotation and why each of our days has 24 hours… Who knew? Alfred Russel Wallace.
The first person to stumble on that phenomenon was the English biologist and explorer Alfred Russel Wallace, who spent eight years in the 1850s exploring what was then called the Malay Archipelago.
His seminal book of the same name is still tremendous reading some 160 years after it was published and, if you want to understand more about this very special part of the world, get yourself a copy.
Wallace was a contemporary of Charles Darwin who, around about the same time as Darwin was having his Origin of the Species ‘ah ha moment’ in the Galapagos, was having his own revelation in what is now Indonesia.
As he made his way through the main islands of the archipelago, Wallace realised that the flora and fauna he was meticulously documenting were different in the east and the west – but did not know why…
Instead, he drew what became known as the ‘Wallace Line’ on a map of the archipelago, denoting where the difference in flora and fauna was most apparent.
Wallace had no way of knowing it, but the line that he drew is basically the main path of the Indonesian Throughflow as those waters of the northwest Pacific Ocean make their way south to the Indian Ocean!
The massive flow of water creating a physical barrier that had separated the flora and fauna of the east of the archipelago from those in the west.
Nature’s supply chain
When the creatures in our oceans die, they sink to the bottom and decompose, becoming part of the dense layer of detritus on the seabed.
Rich in nitrogen and phosphorous, those nutrients in the northwest Pacific Ocean are sucked up from the depths by upwellings created by the Indonesian Throughflow as it flows toward land.
Thus, does life in the ocean come full circle, as the nutrient-rich remains of those dead organisms are delivered to the living ones hungry for sustenance.
And then, as the waters of the Throughflow head south through the archipelago, the eggs and larvae of those reefs and ecosystems are transported and distributed through the archipelago. It’s basically a perfectly evolved supply chain brought to us by nature!
Where to dive in Indonesia
To understand where to dive in Indonesia, simply follow that supply chain through the archipelago and look for where it touches land – with it all starting where the Throughflow makes first contact in Raja Ampat.
Raja Ampat
Raja Ampat is the crown jewel of the area known as the Bird’s Head, located on the western tip of the huge island of New Guinea. Raja Ampat means the four kings – the main islands of Waigeo, Salawati, Batanta and Misool.
Now a self-governing regency, the total area of Raja Ampat covers some 40,000 km² of water with about 1,500 smaller islands and is roughly the same size as Taiwan.
New Guinea is the second largest island in the world after Greenland and was divided in two by the colonial powers who first came to the archipelago in the mid-16th century looking for the source of the fabled spice trade.
The eastern half now forms the mainland of the independent country of Papua New Guinea, and the western half is the Indonesian province of West Papua.
At the peak of the diving season from November through to February, up to 100 liveaboards operate in Raja Ampat and on land there are now some 20 land-based dive resorts.
And yet as recently as the late-1980s, there was just one liveaboard and one beach camp offering diving there!
What drove that exponential growth and continues to draw divers to the area is Raja Ampat’s incredible marine biodiversity, with surveys of the area identifying over 600 species of hard coral (nearly 75% of the world’s total) and over 1,700 species of reef fish – more than any other similarly sized region on the planet.
Did you know?
In Raja Ampat, you will find over 1,300 species of coral reef fish and 600 species of hard coral within the Birds Head Seascape – 75% of the world’s entire species!
Halmahera
The large, starfish-shaped island of Halmahera is located roughly halfway between West Papua and Sulawesi in the far north of the archipelago.
Remote and sparsely populated for its size, the island is swept on all sides by the Indonesian Throughflow and should have marine biodiversity approaching the levels of Raja Ampat.
It most probably did at one time but dynamite and cyanide fishing, the twin scourges of the archipelago, have wrought horrendous damage to large areas around Halmahera.
There are still some excellent areas to dive, but they are remote and mainly accessible from a liveaboard as land-based diving is limited – but growing now that the pandemic has (hopefully) passed.
Almost no liveaboards do dedicated trips around Halmahera, instead those that follow the monsoonal weather patterns and transit through the area on the way from Raja Ampat to North Sulawesi are the way to go.
That said those locations that can be reached, like Djoronga Island at the southern tip of Halmahera and the Patintie Strait between Halmahera and the large island of Bacan offer some great diving.
Similarly the journey from Raja Ampat to Halmahera, and from there to North Sulawesi offer the chance to dive the very remote and exciting Pisang (banana) Island in the middle of the Halmahera Sea and the Goraici Islands in the Molucca Sea.
Sulawesi
Roughly the size of the south island of New Zealand, Sulawesi sits right in the path of the Indonesian Throughflow and its western coastline is effectively the final landmass on the Austro-Malayan Division (eastern) side of the Wallace Line.
Known in Wallace’s time as the Celebes, Sulawesi is probably best known for the seafaring Bugis of the south near Makassar. Their locally built Pinisi wooden schooners have been used for centuries to follow the monsoonal trade winds around the archipelago.
While trading was their main game, they also indulged in a significant amount of sea piracy and were much feared by the European explorers and are the source code of the English saying ‘watch out for the boogey man’…
There is some great diving to be had in both North and South Sulawesi, but the north is more well known because of the excellent diving to be had in the Bunaken Marine Park on the western side of the tip of North Sulawesi, together with the incredible exotic critter diving in the Lembeh Strait on the eastern side.
Plus, further north are the islands of Bangka and Gannga, which also have great reputations for excellent diving, while to the south are the Gorontola, Una Una and the very upmarket and expensive Wakatobi dive resort.
Maluku
Formerly known as the Moluccas, the islands of this province were what the European explorers were looking for when they came searching for the ‘spice islands’ of the East Indies.
The Spanish and the Portuguese came first but were supplanted by the Dutch with their bigger ships and better guns.
Then the British turned up and made their presence felt, but the Dutch ultimately prevailed with their East Indies Company effectively ruling the archipelago until the independent country of Indonesia emerged after World War Two..
Back in the 16th century cloves, nutmeg and mace were the only way to flavour and preserve meat, plus, they were perceived to offer a degree of protection from the deadly plagues that regularly ravaged Europe.
Almost as valuable as gold, fortunes were made trading those rare and exotic spices. The only place in the world they grew was on the very remote Banda Islands and the European explorers wanted to cut out all the Arab and Venician spice trade merchants with their greatly inflated prices.
The Dutch used the island of Ambon as their base in the Moluccas and left behind a strong Christian legacy in the area that now has the largest Muslim population in the world.
The city of Ambon is the provincial capital and has a great combination of excellent critter diving in the large bay that forms the entrance to the main harbour, plus some nice wide-angle diving along the south coast.
The Banda Islands to the south are a quite special and unique diving location and the huge Banda Sea offers the possibility of some amazing encounters with blue and sperm whales, schooling hammerheads and the isolated sea snake infested Gunning Api, or ‘snake island’.
Bali, Nusa Penida and Nusa Lembongan
Where the Indonesian Throughflow touches the north and east coast of the Island of the Gods, together with its close neighbours Penida and Lembongan, is where you will find excellent marine biodiversity.
But be warned… the Lombok Strait, between Bali and the island of Lombok, is the main exit for the waters of the Indonesian Throughflow into the Indian Ocean.
With the east coast of Bali experiencing some huge currents and both Nusa Penida and Nusa Lembongan sitting right in the middle of it! Most operators are well aware of the dangerous locations are and will avoid them like the plague… Make sure you do too!
Tulamben and nearby Amed on the north-east coast are the main locations for diving in Bali, with Padang Bai on the east coast also very popular.
There are a few interesting critter diving spots further west from Tulamben and on the western tip of Bali, there is some good diving at Menjangan Island and the Secret Bay critter site at Gillimanuk.
Did you know?
The liberty ship was hit by a Japanese torpedo and then beached near Tulamben. In 1963, the eruption of Mount Agung caused the vessel to slip off the beach, and it now lies on a sand slope in 9-30m of water. The wreck is about 130 metres long with the shallowest part at 5m and the deepest on the other side of the wreck at about 30m.
The Lesser Sunda Islands
East from Bali are the chain of islands called the Lesser Sundas that form the southern rim of the archipelago, with the area around Komodo being the main location for diving.
Komodo has experienced similar exponential growth in diving tourism as Raja Ampat and the main town of Labuan Bajo is now virtually unrecognizable from what it was just ten years ago.
There is some great diving to be had in the Komodo area, but it does get crowded and lacks the incredible biomass that Raja Ampat has.
Other locations in the Lesser Sundas are the south and east coasts of Lombok, the nearby islands of the Gilis (which are now the technical diving centre of Indonesia) and Alor further to the east.
In summary
Trying to summarise the diving in Indonesia is like evaluating the length of a ball of string – it’s not an easy task. But the key to understanding it all is that massive flow of water through the archipelago. Understand it, follow it and you will be on the right track – you won’t be disappointed!
Don Silcock
Don is Scuba Diver’s Senior Travel Editor and is based from Bali in Indonesia. His website has extensive location guides, articles and images on some of the best diving locations in the Indo-Pacific region and ‘big animal’ experiences globally.
FAQ: Diving in Indonesia
Q: Why is Indonesia such a popular diving destination?
A: Indonesia sits at the heart of the Coral Triangle, the most biodiverse marine region on the planet. With more than 16,000 islands and the nutrient-rich Indonesian Throughflow, it offers unmatched marine life encounters, coral reefs, and diverse dive environments.
Q: What is the Indonesian Throughflow and why does it matter for divers?
A: The Indonesian Throughflow is the world’s largest movement of water, flowing from the Pacific to the Indian Ocean through the Indonesian archipelago. It delivers nutrients, eggs, and larvae across the region, fuelling vibrant reefs and ecosystems that divers experience today.
Q: What are the best places to dive in Indonesia?
A: Top diving areas include Raja Ampat for biodiversity, Komodo for dramatic currents and mantas, Bali for wrecks and macro life, Sulawesi for Bunaken and Lembeh Strait, and the Banda Islands for pelagic encounters.
Q: When is the best time to dive in Indonesia?
A: Indonesia offers year-round diving, but the best conditions depend on the region. Raja Ampat’s peak season is November–April, Komodo is best May–September, while Bali and Sulawesi can be dived most of the year with varying conditions.
Q: Is Indonesia suitable for beginner divers?
A: Yes, many areas like Bali’s Tulamben and Amed are beginner-friendly. However, advanced divers will find thrilling currents in places like Komodo, Nusa Penida, and Raja Ampat, making Indonesia suitable for all levels.
Q: What kind of marine life can I expect in Indonesia?
A: Expect everything from tiny critters like pygmy seahorses and nudibranchs to big animals such as manta rays, reef sharks, whale sharks, and schooling hammerheads. Indonesia is famous for both macro photography and wide-angle pelagic action.
Q: How many dive sites are there in Indonesia?
A: With over 16,000 islands and hundreds of recognised dive regions, Indonesia offers thousands of dive sites. From famous wrecks like the USAT Liberty in Bali to remote reefs in Raja Ampat and Banda, the choices are nearly endless.
This article was originally published in Scuba Diver ANZ #62
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