If you live outside the USA (not USA citizens), and you want to WWOOF in the Hawaii, obtaining the correct visa is your responsibility. WWOOFing is not paid work and will not help you obtain a work visa or work permit. The United States has very strict labor and immigration laws, and requires travelers who are here to "work" have a work visa. WWOOFing is an educational experience not a work opportunity. In order to avoid misunderstandings with immigration officials, please explain to them that you are here as a tourist, interested in learning more about the United States sustainable and organic farming movement. Most people enter the US with a tourist or visitors visa, communicate their intentions to immigration, and are allowed in without a problem.? If your focus is not to learn about the organic farming movement and you are just looking for a volunteering opportunity, than you will need a work visa. If you say that you are coming to "work or volunteer on a farm, and you don't have a work visa, they most likely WILL NOT LET YOU ENTER THE USA / HAWAII. We are not responsible for any problems you may experience with immigration, please make sure you understand the laws and clearly communicate your intentions.