Spa World — Multi-Floor Onsen Theme Park

Spa World (スパワールド世界の大温泉) in Shinsekai is an 8-floor onsen (hot spring) complex themed around world bathing cultures — European zone (4F) features Roman baths and Finnish saunas, Asian zone (6F) has Japanese rotenburo (露天風呂, outdoor baths), Korean jjimjilbang, and Balinese spa aesthetics. The facility contains 16+ different bath types using natural hot spring water pumped from 1,000m underground.

The complex is foreigner-friendly (tattoos allowed, unlike traditional onsen) and co-ed in swimsuit areas (bathing zones are gender-separated and nude, per Japanese onsen rules). The 24-hour operation and ¥1,500 all-day entry make it popular with budget travelers, families, and late-night travelers needing sleep space (napping in common areas permitted). The facility bridges authentic onsen culture with theme-park entertainment.