In an article over at Yahoo! Japan’s R25 digital magazine, a member of the Nihon Onsen Kyoukai (Japan Hot Spring Association) let readers in on three little-known, not to mention rather unusual, hot spring locations that are sure to leave you with plenty of tales to tell family and friends.

With more than 3,000 hot spring locations scattered across Japan, it’s little wonder that we’ve all by now seen plenty of photos of bathing monkeys, steaming pools of water surrounded by undisturbed snow, or young ladies wrapped in towels taking a dip. But for the onsen extraordinaire, once the spots listed in all of the travel guides have been checked off, where is there left to turn? The Japan Hot Springs Association’s Fuyama-san has some very interesting recommendations:

“If you’re looking for something a little different, I recommend Toyotomi Onsen, situated at the northernmost point of Hokkaido, which is known for being a ‘petroleum hot spring.’”

Did she just say petroleum? As in the stuff we pump into our cars to help us get to Starbucks faster!?

“That’s right; there’s a very thin layer of petroleum oil floating on top of the spring water here, which means there’s an ever-so-slight whiff of gasoline. But the oil in the water is actually very good for skin conditions, and so hot spring fans from all over the country flock here each year.”

Next up is Akita Prefecture’s Tamagawa Onsen resort, which Fuyama-san informs us contains springs whose water—with a pH of 1.1—is by far Japan’s most acidic. But at 10 times the acidity of ordinary lemon juice, can that really be a good thing?

“It certainly makes your skin tingle all over! The water here is said to be beneficial to those with high blood pressure or suffering from arteriosclerosis (the hardening of the arteries). For this reason, the resort has many visitors who come to stay for long periods of time, and there’s even self-catering accommodation available.”

Finally, Fuyama-san introduces us to a hot spring resort that, while not boasting petroleum-membrane or skin-tingling water, has a very special, centuries-old custom of its own. Located in Tottori Prefecture in southern Japan, the Iwai Onsen resort invites visitors to sing a little while taking a dip!

“With over 1,200 years of history, this resort has a custom known as yu kamuri (literally, “hot water cap”). After soaking in the water for a while, guests sing what is known as the yu kamuri song while placing their hand towel on top of their head and ladling the hot water over it. It’s said that this custom helps the effects of the water spread through the entire body.”

So the next time you're looking for something different in your onsen experience, why not give one of these a try?