For visa requirements to visit Kundur, please see the main Indonesia page.
Kundur's port of Tanjung Batu is NOT designated as a visa-free or visa-on-arrival entry point. Those requiring visas should get one beforehand. For visa-free nationalities, there does not seem to be a problem entering or leaving Indonesia via Tanjung Batu.
As Kundur does not have an airport, all visitors arrive by ferry. Most connections are with neighbouring islands, e.g. Tanjung Balai on Karimun, and the Sumatra "mainland". Direct ferry services to Singapore have been terminated, so you'll need to detour via Batam or Bintan.
From Other Riau Islands
To/from Batam via Karimun Island: Several companies operate ferries between Tanjung Batu and Sekupang, the main domestic port on Batam, stopping at Tanjung Balai on Karimun on enroute.
The Miko Natalia 3 Tel: +62-779-21922 in Tanjung Batu; +62-777-21207/31895 in Tanjung Balai; +62-778-321980 in Sekupang, Batam links Tanjung Batu with Tanjung Balai, the main town on Karimun Island several times daily. Between Tanjung Batu and Tanjung Balai, tickets cost Rp. 46,000 one-way before port taxes. Journey time is over one hour, longer if stops are made at islands along the way.
The Marina Batam also operates this route.
To/from Karimun Island only:
The Ocean Indoma operates ferries between Tanjung Batu and Tanjung Balai twice a day.
To/From Tanjung Pinang, Bintan
One daily speedboat operated by SB Giam Mas Tel: +62-779-431589 in Tanjung Batu departs daily from Tanjung Batu at 0745 for Tanjung Pinang, the main town on Bintan. The boat returns to Tanjung Batu on the same day, departing Tanjung Pinang at 1200. The boat has scheduled stops at Galang Island and Moro on Sugibawah Island, while unscheduled stops may be made at various little settlements along the way. Journey time is about two and a half hours each way. The fare from Tanjung Batu to Tanjung Pinang and vice-versa is Rp 130.000 before port taxes. On the other hand, Tanjung Batu to Galang/Rempang costs Rp 95.000, Moro to Galang/Rempang costs Rp 50.000. From Tanjung Pinang to Moro is Rp 95.000, Galang/Rempang is Rp 45.000.
From Sumatra
Boats link Tanjung Batu with various Sumatra mailand ports, such as Tembilahan in Riau province, and Kuala Tungkal in Jambi.