Bintan is only about an hour by ferry from Singaporee (Tanah Merah Ferry Terminal). Ferry operators include:
If you are in Indonesia, there are also domestic flights to Bintan's Raja Haji Fisabilillah Airport. Riau Airlines provides connections to Jakarta, Pekanbaru, Palembang, Jambi and the remote Natuna Islands whilst Sriwijaya Air offers daily flights from Jakarta.
If you are based in Batam, you can even drive over to Bintan via the car ferry or 'RoRo'.