As a country that consists of more than 17,000 islands, Indonesia has so many good places for sea diving, some of which are the best in the world.
Please find below an information quoted from Dive the World.
Diving in Indonesia
The Garden of Eden
Generally accepted to be the world's best country for sea life, Indonesia has more marine diversity than anywhere on earth. Slap bang in the middle of the 'Coral Triangle' of diversity that extends from Australia to the Philippines and across to Borneo and into the South Pacific, this country is at the core of the ocean's heart, where the marine variety suggests life in the sea began.
You can dive here now and experience all the wondrous fish and other marine life in these nutrient-rich seas. From encounters with big pelagics around the cool waters of Komodo, cruising over pristine fields of coral in Raja Ampat, marvelling at the enormous volumes of fish in the Banda Islands, to photographing the outrageous critters of Sulawesi, Indonesia diving is unsurpassed.
There are packages to suit all needs including resort diving in Bali and Sulawesi where you can stay in comfort on the doorstep of world-class dive sites where marine biologists, photographers and pleasure divers come to marvel and the species numbers and variety.
For many, diving is best on one of the liveaboards to Komodo and beyond, into the seemingly unchartered territory of Irian Jaya. These trips offer the chance to cruise over crystal seas from Bali to the legendary islands of Komodo and Rinca where the dragons of folklore roam. Beyond Komodo lies some of the most exhilarating frontier diving there is, around the Banda Islands and Raja Ampat where there are few boats and only serious pleasure-seeking divers. Fantastic diving is virtually assured.
Such a vast and varied dive destination as Indonesia is very difficult to limit to just a few highlights but any consideration of a dive holiday here should bear in mind at least the following areas:
Raja Ampat - one of the few destinations left which truly allows you to feel like you are a pioneer - to boldly dive where no man has dived before. You can marvel at the incredible topside scenery of Irian Jaya, sail through waters where so few boats venture and experience some of the most impressive diving in Indonesia ... and therefore the world. For those who want to get away from it all and dive in a remote paradise but not compromise on comfort then Raja Ampat liveaboards are the choice for you.
Komodo National Park - the islands of myth and legend where dragons roam, are surrounded by rich nutrient-filled waters where a kaleidoscope of colour and life awaits you. Mantas, dolphins and sharks compete with critters galore, all against a riot of soft coral colours. Komodo liveaboard trips allow you to visit the many varied sites around this awesome marine park, some starting in Bali and visiting all the best sites along the way.
A short drive from here is the Lembeh Strait - the undisputed King of muck diving destinations. This small calm stretch of water is where macro-photographers and critter hunters agree offers the most impressive diving. Along the black sandy floor you will encounter more bizarre and fascinating marine creatures than you could wish for. Add to this the Sangihe Archipelago and Bangka Island, and you can see why many divers return time and again to Sulawesi, an island that can fulfil all your dive dreams.
Banda Islands - the Banda Sea may be located between the better known destinations of Komodo and Raja Ampat, but for those in the know it deserves its own reputation as one of the world's best diving regions. Diving in Banda means experiencing incredible variety of both large and small. Big pelagics and large schools abound. The reefs are healthy and thriving. Consider on top of this that many different species of whales and dolphins are often sighted, and you begin to get the picture. Diving here is varied, colourful and fascinating as it takes in the critter haven of Ambon as well as the Banda Islands.
How to Dive Indonesia
It all depends on the diving you want to do. We recommend 2 ways: Resort stays in Sulawesi and Bali will allow you the opportunity to base yourself close to some of the finest diving in the world. See our Indonesia resorts section.
Alternatively, liveaboards in Indonesia are always a top choice for those who want to see more than any land-based stay can offer. Liveaboards can take you around the best of Northern Sulawesi, east from Bali to the legendary island of Komodo, Wakatobi, or into the inspiring frontier territory of the Banda Sea and Irian Jaya. Breathtaking diving, fantastic boats and inspiring topside scenery all await you here. Check out our Indonesia liveaboards.
You can dive in Indonesia at any time of the year. Generally speaking for such a vast country, April to December are the best times to go since rainy season is more or less between the months of January and March. That said many places, such as Sulawesi, have excellent conditions at this time so be sure to check the diving season details for your particular destination of choice. The Indonesia liveaboards season is all year round.
Great for: Small animals, underwater photography, wall dives, wreck diving, drift dives, reef life and health and advanced divers
Not so great for: Beginner divers
Depth: 5 - >40m
Visibility: 10 - 80m
Currents: Can be very strong
Surface conditions: Calm
Water temperature: 19 - 30°C
Experience level: Intermediate - advanced
Number of dive sites: ~500
Access: Scuba resorts and liveaboard charters
Recommended length of stay: 2 - 4 weeks