BY AIR

INTERNATIONAL

In addition to the national airline Garuda, many international carriers also fly to Jakarta and Bali, which are the two major gateways to the country.

Some airlines, including low-cost ones like Air Asia, Tiger Airways and Jetstar, also fly from the neighbouring countries to less usual but interesting destinations like Bandung, Solo, Lombok, Makassar, Balikpapan, Banda Aceh or Padang in addition to covering the major routes to Jakarta, Surabaya, Bali and Medan.
In fact, if you can't find a good fare from your home country straight to Indonesia, it may well be worth checking if you can do better by flying first to Bangkok, Kuala Lumpur or Singapore, then picking up a connecting flight to Indonesia on one of these budget airlines!

WITHIN INDONESIA

The domestic air travel industry in Indonesia is now very competitive, which can make flying around the country a real bargain on longer distances.
Flying shorter distances within individual regions can be surprisingly pricey though!

To the frustration of many foreigners, most Indonesian domestic airlines don't have a well-functioning online booking system. That's simply because most Indonesians don't use the Internet, so tickets are generally sold through local travel agents.
This can make it difficult to book your domestic flights within Indonesia well in advance from abroad difficult or even impossible.
There is little reason to worry though - tickets are generally readily available even on the day you want to travel, and won't even be necessarily more expensive if bought so late! So you can just wait till you actually arrive in Indonesia and buy them there.
Domestic airlines have offices at the airports, so you could buy your tickets right upon arrival at the airports in Jakarta or Bali, the two main international gateways.
If still keen on trying to book in advance, the airlines with the most reliable and user-friendly online booking-systems by far are Sriwijaya and Air Asia Indonesia, followed by Garuda. Unfortunately, the very popular Lion Air's flashy website mostly rejects foreign cards at the end of the booking process.

If you can't book tickets directly on the airlines' websites but are keen to book in advance anyway, you can book through an Indonesian travel agent, paying a commission to them, of course. Ones that friends of mine have used and found OK are are Perama and Itravelindonesia.

                                                    BY SEA

INTERNATIONAL

The major international shipping connections are between Malaysia and Sumatra, or Singapore and the Riau Islands.
You can also take boats from Sabah (East Malaysia) to Kalimantan.
Boat services from the Philippines to Sulawesi and Papua New Guinea to Indonesian Papua have all but ceased, and there are no connections from Australia either.

WITHIN INDONESIA

Travelling by sea is the classic way to explore Indonesia, and the possibilities are almost unlimited.
The government owned Pelni is the major passenger carrier, and its huge ships connect all major ports of the archipelago to Java, mostly operating on fortnightly schedules.
On shorter runs there will be a choice of private services ranging from modern hydrofoils to small wooden boats and rusty Perintis cargo ships.

                                                    BY ROAD

INTERNATIONAL

Indonesia shares land borders with Malaysian Borneo, East Timor and Papua New Guinea.
All these borders are now open for travellers, but note that you need a visa in advance to enter Indonesia this way.

WITHIN INDONESIA

All the bigger islands have a road network - most extensive on Java, least developed on Papua. Wherever there are roads there will be public transport. On the most popular routes this will mean buses, sometimes big and comfortable ones with air-con, on lesser ones shared Kijang taxis, on really remote tracks ojek motorcycle taxis.
Renting a car is a better idea with a driver!