The ferry jetty taking you to Penang island is located in Butterworth, next to the Butterworth main bus station (where you can take express buses to other towns/states/Singapore/Hatyai) as well as the KTM train station.
If you take a train from Bangkok or Hatyai to Butterworth, when the train arrives (usually at about 1 to 2pm local time), you can walk up the pedestrian overhead walkway to the ferry station. You can a ferry to Penang (sorry, I do not know the charges- years ago, I paid 80 sen). If travelling by car, it is RM7.70.
The view would be what you will see:
Of course, I have resized my photos to low resolution so that it is easier to load. As such, the pictures do not do justice to the actual feeling of being there. On good windy and cloudy days, the breeze blowing is really heavenly.
On your left in the ferry, you will see the Penang bridge. It’s one of the longest bridge in the world (hmm…. still number 3?)
When I took this picture, you can seel the weather is a bit cloudy. It was really windy.
See the tall building in front of you? It is Komtar building- where there’s a bus station and often used as a landmark.
The trip takes about 15 to 20 minutes. And if you take the ferry from the island back to Butterworth, it is free of charge. You are only charged when you want to cross over to Penang.
When I was staying in Penang, I sometimes took a bus to the jetty at night- when it was quiet and calm. Then, I would just take the ferry to Butterworth and another round trip back. The breeze always seemed to clear my head a little- no matter how heavy it felt.