This is a monthly magazine produced by the Public Relations Office of the Government of Japan, where you can find a very simple run-down of what onsen are and what they mean to Japanese people. Orientation comes in a flash, with a two-question quiz at the end. The magazine is vetted by local and national officials, so you can count on the information to be reliable, whatever you're looking for.

Ignore the 2011 in the title: This is still a great place to start your search, and one of the best English summaries of Japan’s major resorts. Just don't use the top left booking widget—it self-immolated in 2013. Instead, select a region and book through the individual hotels.

This site is a mystery. We have no idea who made it or how to contact them. Despite the imperfect English, it offers a deluge of information on a number of topics with lots of videos and pretty pictures. The onsen section goes over everything from etiquette to history, major water types and famous resorts you might want to check out.

Don’t be fooled by the title: This site is first and foremost about promoting health through onsen and nothing else. But it conducts research, performs surveys and offers its own suggested rehabilitation programs, so the makers have a lot of knowledge under their obi. Their site presents a cute and concise run-down of all the basics, including water types, etiquette and tips for getting the best health benefits during and after your soak.

Texan in Tokyo is a personal blog run by Grace Buchele Mineta, highlighting her adorable adventures in Japan with her equally adorable husband, Ryosuke. A comic artist with a unique personal style, Grace's illustrated observations on day-to-day life form the backbone of her site. In addition to all that, she's a huge onsen fan, and her detailed how-to videos have been invaluable in filling out our big hot spring feature. If you have any questions about onsen—down to the smallest details—Grace will set you straight.