If you would like to go to Penang, Malaysia across Malacca Straits, you can use a ferry from Belawan Harbour, North Sumatra, Indonesia directly to Jetty Harbour, Penang. It takes 5 hours with ticket fare RM 150 (around Rp 500.000).
I ever use this way when travel back from Penang to Indonesia on January 2009. As long as the weather is okey, the travel is safe. At the Malacca Straits, you will see some container ships, nice sea scenery and beautiful long bridge at penang before arriving at Jetty Harbour. Have a nice trip through this way.
