Products · Saunas · Almost Heaven Saunas
Almost Heaven Blackwater 4 Person Cube Sauna
Reader ratings
A US-made cedar cube sauna with a Finnish Harvia stone heater; the Spirit option matches Intertek’s UL 875 listing. The maker rates it to 194 °F, in the range of the Finnish studies. About $11,300 with heater; 240 V.
Best for People who want a traditional outdoor sauna at the heat the long-term Finnish studies used, and who have the budget, a level base and an electrician.
- Our quality rating
- Good (4 of 5)
- Price range
- Premium
- Verified marks
- Heater only: ETL/cETL Listed (UL 875, CSA E60335-2-53)
- Size
- Outdoor cube, 84 3/8 in W x 71 in D x 85 7/8 in H outside; seats 4 to 6
- Made in
- Made in the USA (West Virginia)
approx. $11,268 with a 9 kW Harvia heater
See it on Almost Heaven Saunas’s site →We are not affiliated with Almost Heaven Saunas. This link goes to the maker’s own page, with no tracking code. How we're funded.
Reader ratings & reviews
– out of 5
Loading ratings…
Rating breakdown
- 5 stars 0
- 4 stars 0
- 3 stars 0
- 2 stars 0
- 1 star 0
Have this product? Please rate it.
Check your email
We sent a sign-in link to . Click it and you’ll come straight back here, signed in. It expires in 15 minutes; check your spam folder if it doesn’t show up. Thank you for helping the community!
Your review
Reviews are personal experiences, not research, and they never change our quality ratings. Every review is read by our team before it appears.
How we evaluated it
Why we chose it What put it on our list
- Traditional heat. The maker lists dry heat at 140 to 194 °F (60 to 90 °C), and its manual calls 160 to 185 °F or more typical. The Finnish cohort studies on our heat therapy page used saunas at about 80 °C.
- One heater option has an independent safety listing. Intertek’s ETL directory lists Harvia’s sauna heaters to UL 875, and Almost Heaven’s part number for the Spirit option, HSPE90U1M, fits a listed model pattern. The Virta’s part number (HL9U1) lacks a suffix the listing shows, so choose the Spirit. The quick-ship kit comes only with the Virta.
- Unfinished cedar. The maker’s FAQ names Rustic Western Red Cedar for the cedar option. The manual says the outdoor sauna’s wood is untreated and warns never to treat the interior unless the product is approved for saunas.
- Plain build. The page lists 1 3/8 in ball-and-socket boards, stainless steel bands, hinges and fasteners, and tempered glass. It names no glue or finish for the cedar version.
- Support is spelled out: a limited lifetime warranty against manufacturing defects, and a Harvia heater warranty of 1 year on the elements and 5 years on other parts.
Trade-offs What to weigh before you buy
- It costs about $11,300 with the heater, stones and LED light (Rustic Red Cedar), plus an electrician to hard-wire a 240 V, 45 A circuit. Almost Heaven quotes installation from $1,400. Standard orders ship in 8 to 12 weeks.
- Choose Rustic Red Cedar if you want bare wood inside. The Onyx version is stained inside and out with a stain the maker does not name. Its FAQ calls Onyx stained hem-fir, while the retailer calls it cedar. It costs about $1,051 more.
- The product page says only “premium North American cedar”. The species comes from the maker’s FAQ, and we found no emissions or odor test on the wood.
- The warranty covers manufacturing defects only. It does not transfer to a second owner and applies in the contiguous US.
- Ask a doctor first if you have heart disease, or are pregnant, and skip alcohol before and during a session (see our hot baths page and the manual’s own warnings).
What to know Details worth knowing first
A traditional sauna heats the air with a stone heater, and that is the kind the long-term Finnish studies followed, at about 80 °C several times a week. Our heat therapy page explains what those studies can and cannot show. The Blackwater is a prefab outdoor cube: a cedar room, a glass door and a 9 kW electric heater that an electrician wires in.
What we could check is the heater. Intertek’s ETL directory lists Harvia’s sauna heaters to UL 875, and the part number Almost Heaven uses for its Spirit option fits that listing. The Virta’s part number is missing a suffix, so choose the Spirit. What rests on the maker is the temperature range, the cedar species and the claim that the wood is untreated. Almost Heaven has belonged to Harvia since 2019, so the cabin and the heater come from one group.
Read the price carefully. Almost Heaven’s $11,268 includes the heater, stones and a light. The retailer Finnish Sauna Builders sells the kit alone for $9,998, with the heater extra. Pick the plain cedar version if you want bare wood inside, and ask a doctor first if you have a heart condition or are pregnant.
Quality & testing How it measures up against our checklist
- Third-party tested
- Yes
- Tested by
- Intertek (ETL listing of the Harvia heater)
| What we checked | What we found |
|---|---|
| Heat that matches the research Maker’s claim | The maker lists dry heat at 140 to 194 °F (60 to 90 °C) and its manual calls 160 to 185 °F or more typical. These are the maker’s figures; we have no measured cabin temperatures. |
| Untreated, low-odor wood Maker’s claim | Rustic Red Cedar, which the maker’s FAQ calls Rustic Western Red Cedar, described as raw and untreated. No glue or finish is mentioned for it. The Onyx option is stained inside and out with an unnamed stain. We found no emissions or odor test. |
| Safety certification: Spirit heater option Verified | Intertek’s ETL directory lists Harvia Finland Oy sauna heaters to UL 875 and, in a sister listing, CSA E60335-2-53. Almost Heaven’s part number for the 9 kW Spirit, HSPE90U1M, fits the listed Spirit pattern (HSPE, 90, U1, M). The listing covers heaters, not the cabin, and shows no certificate number or date. |
| Safety certification: Virta and wood-burning options Not verified | The Virta (HL series) is in the listing, but the listed pattern ends in a suffix such as S or (Q) and Almost Heaven’s part number, HL9U1, has none. The M3 wood-burning kit is a different product we did not check. |
| Materials that hold up to heat Maker’s claim | Not a tent or blanket. A rigid cedar room with stainless steel bands, hinges and fasteners and tempered glass, all as described by the maker. |
| Electric and magnetic field claims Maker’s claim | The maker makes no EMF claim. The only electrical parts are the heater and an LED light. |
| Marketing claims Maker’s claim | The product page makes no detox, weight-loss or calorie claims. |
| Recalls Verified | A search of the US Consumer Product Safety Commission recall database on 2026-10-22 found no recall naming Almost Heaven or Harvia. |
What the labels mean
- Verified We opened an independent record that confirms it: a certifier’s listing, a regulator’s list or a lab report. It is linked under Sources.
- Maker’s claim The maker says so on its own page or label. We read it but found no independent record.
- Not verified We looked and could not confirm it, or the maker does not say. Treat it as unknown.
Sources Where our facts come from
- Almost Heaven Blackwater 4 Person Cube Sauna: maker’s product page. Maker’s page. Price, specifications, heater options and the 140 to 194 °F range. Open ↗
- Almost Heaven FAQ: lumber choices and treatment. Maker’s page. Names Rustic Western Red Cedar and calls Onyx stained hem-fir. Open ↗
- Blackwater installation and owner’s manual (PDF). Maker’s page. Untreated wood, typical 160 to 185 °F, safety warnings. Hosted by the retailer. Open ↗
- Intertek ETL directory: Harvia Finland Oy, Electric Dry Bath Heater (UL 875). Certifier or regulator listing. Lists Spirit (HSPE) and Virta (HL) model patterns, which end in a suffix for the Virta. A sister listing covers CSA E60335-2-53. Open ↗
- Intertek ETL directory: Harvia Finland Oy, Electric Sauna Heating Appliances (CSA E60335-2-53). Certifier or regulator listing. The cETL listing for the same heater families, under the trade names Harvia and Sentiotec. Open ↗
- Almost Heaven warranty. Maker’s page. Open ↗
- Almost Heaven about page: joined the Harvia family in 2019. Maker’s page. The sauna maker and the heater maker are now the same group. Open ↗
- Finnish Sauna Builders: Blackwater kit page. Independent source. Retailer page with the kit-only price. Open ↗
- US Consumer Product Safety Commission recalls. Certifier or regulator listing. We searched CPSC’s recall data on 2026-10-22 for Almost Heaven and Harvia and found no recall. Search the site yourself for any later notice. Open ↗
Where to buy Other stores and the prices we saw
- Finnish Sauna Builders (retailer) approx. $9,998 for the sauna kit only (Onyx approx. $11,498). A retailer, not the maker. Its page says heaters, lights and stones are sold separately, while Almost Heaven’s price includes them, so compare totals.
- Almost Heaven quick-ship kit approx. $11,268 (Onyx approx. $12,319). Same price as the standard order, which ships in 8 to 12 weeks. The maker says this version ships in 3 to 5 days. It comes only with the Virta heater, whose part number we could not match to the listing.
Prices as we saw them on October 22, 2026. They change often. These links carry no tracking code and earn us nothing.
Alternatives Other options to compare
- Almost Heaven Salem 2 Person Barrel Sauna Same maker, wood and warranty in a smaller barrel. About $6,700 with a 6 kW Harvia Spirit heater.
- Dundalk LeisureCraft barrel and cabin saunas Made in Ontario. The Canadian Timber line uses eastern white cedar and the Dundalk line uses Western red cedar, with a 5-year warranty. Sold through dealers, so ask what the price includes.