A visa is required for Vietnam, Cambodia and Laos, and Thailand, but it depends on which nationality you are. Some of them are free for your stay for up to 15 days. For Vietnam, you can click here to make an e-visa: https://evisa.xuatnhapcanh.gov.vn/en_US/web/guest/trang-chu-ttdt If you are not on the list of countries that allowed E-visa issuing, we will help you to make a VOA (visa on arrival) at the international airports. For Cambodia: you can make a visa at the international airports then.