onsen 温泉

According to the 温泉法 onsen hō (Japanese Hot Spring Act), an onsen is defined as ‘hot water, mineral water, and water vapor or other gas’. But we all know there’s no onsen without a whole bunch of naked strangers, too.

Temperature note: When locals say 熱い atsui (hot), they mean it. Some baths can exceed 40°C. If you see hard-boiled eggs, maybe try a different pool.

Misty manners:

• Wash thoroughly at the washing stations before entering
• No swimsuits
• Towel on head, not in water
• Small towel for modesty (until you stop caring)
• No photos (obviously)
• Tattoos = no entry
• Accept that you’ll eventually make awkward eye contact with another tourist pretending to be comfortable

Steamy statistics:

Japan has approximately 25,000 hot spring sources. About 3,000 onsen establishments make use of these. The other 22,000 are just out there, making random patches of snow melt.

Water varieties:

• 硫黄泉 iōsen (sulfur – smells like eggs, great for health, terrible for date night)
• 炭酸泉 tansan-sen (carbonated – nature’s jacuzzi)
• 塩泉 ensen (salt – your skin will thank you)
• 酸性泉 sansei-sen (acidic – tingles in a good way)

In need of a relaxing onsen visit? Look for these symbols:

• ♨️ (universal onsen symbol, and yes, there’s an emoji for it)
• ゆ yu (means hot water)
• 湯 yu (same meaning, kanji version)