1. Online purchase: Many Vietnamese shipping companies offer online ticket purchasing services. You can purchase tickets through their official website or online travel agency websites. Some popular shipping companies include Bus Express, Pegasus Shipping and Vietnam National Shipping Company.
2. On-site purchase: If you travel in Vietnam, you can go to the seaport or travel agency to buy local air tickets. It may be more convenient and time-saving to buy tickets locally, but it is best to know the local prices and conditions before buying tickets.