4Bangkok · Thong Lo
Let's Relax Onsen and Spa Thonglor
BoutiqueModernRitual
300 Soi Thong Lo
- Onsen
- 750 THB
- Open
- 10:00 to 00:00
- Google rating
- 4.5 · 2,135
- Late
- until midnight
The verdict
Several onsen pools with different minerals, saunas and steam rooms, then a Thai massage, on Thong Lo and open until midnight.
Go late
Dinner on Thong Lo, then an hour in the onsen: several pools, a sauna, steam rooms. It's open until midnight, so there's no hurry.
Finish with a Thai massage or a four-hands one if you're feeling generous. You'll sleep like the city never could.
Why this one
Spa by JW at the JW Marriott scores higher, 9 against 7, but sits 1 km from Nº 1. Yunomori, on Sukhumvit 26, has more reviews but scores 6.
Let's Relax Thonglor gives you the onsen, steam and a full Thai menu with every price online, open later than anything else here.
What guests notice
“It really feels like being at an onsen in Japan! The atmosphere is peaceful, and there are several onsen pools with different benefits to enjoy.”
The Traveller, Google review
“I do not understand why oil massage is double the price of a normal thai massage.”
Darwis Sunaryo, Google review
Skip it if
You want a garden or daylight: this is an indoor onsen. For outdoors, go to Nº 3.
The menu
Prices from letsrelaxspa.com (Thonglor branch), checked 7 November 2026.
Before you go
Daily 10:00 to midnight, on the 5th floor of Grande Centre Point Sukhumvit 55 (a 2026 review), 300 Soi Thong Lo. Ask about the therapist's gender when you book if it matters to you.
Find it
Rating, hours and address from the venue's Google listing, checked 7 November 2026.