Getting to Pulau Bawah
You will need to go to Tanjung Pinang first, the main port town in Pulau Bintan, which is located just below Singapore. From Bintan, you can go by ferry to Anambas, a 7-8 hour trip. Once in Anambas, you'll need to charter a boat to Pulau Bawah.
Alernatively, you take this recently added ferry from Pulau Batam instead.
Once you're in Jemaja, ideally, you depart from Kuala Maras, as the distance to Pulau Bawah is closest from here. The trip takes about 2 hours by speedboat, or 4 hours by pompong, a slower diesel-engine fishing sampan.
Book your plane tickets to Letung here.
The Anambas airport is in Letung and you can fly to Letung from Batam, located just off Singapore, or from Jakarta. This flight operates Monday, Wednesday, Friday and Sunday. (If you're departing from Jakarta, just replace Batam.) Ticket cost should be around 1,500,000 Indonesian Rupiah for a one-way ticket or 3,000,000 Rupiah for a roundtrip, although it can be higher during peak season spells.
Or book direct from Sky Scanner