The town itself is small enough to walk. For the caves, blue lagoons, and surrounding villages, a bicycle is the most satisfying option — flat valley roads make it genuinely easy, and you can stop whenever the views demand it. Bicycles rent for a few dollars a day from guesthouses and shops along the main street. Electric bikes are also available if you want more range with less effort.
Tuk-tuks can take you to the main cave and lagoon sites for a negotiated fare, which makes sense if you're short on time or travelling in a group. Motorbike rental is widely available but the roads around the caves can be dusty and potholed; go slowly. A traditional wooden boat ferry crosses the Nam Song to reach Tham Chang Cave and the villages on the west bank.