My group has 4 travelers and we each have a Swiss Rail Pass. We want to travel from Montreaux or Chillon to Lausanne. Do we need to buy tickets in advance or is that unnecessary?
If you have a Swiss Pass, it is valid on the boats. No other ticket necessary.
You can see the boat routes shown on the official Swiss Pass validity map: https://www.sbb.ch/content/dam/sbb/de/infotexte/uebersichtskarte-sts.pdf
Even if you didn't have a pass, pre-purchase is unnecessary. You can buy on the day.
Thank you Chris.