Adventurous Theme Update? From V1.0 to current

Hello, I designed a site a few years ago with this theme, and over the years the person handling the site did not update the theme. My question is, do I need to update to each version or can I update to the current 4.s version and skip the other versions? If I have to update to lower versions first, where do I find them? Thank you for you help. Lorayne