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Coamo hot springs (Baños de Coamo): what to know before you soak
Coamo hot springs (Baños de Coamo) are Puerto Rico’s best-known natural hot springs, in the southern municipality of Coamo. In US Geological Survey samples, the spring water measured about 43 °C (109 °F). A hot soak can feel relaxing, but we found no solid evidence that it treats disease. We could not confirm that the pools are open today, so check before you travel. In the water, keep your head above the surface and get out if you feel dizzy.
Is it an emergency? Call 911.
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Is this an emergency?
This is not an emergency service. Call 911 or go to the nearest emergency room if you have:
- Fainting, confusion or slurred speech during or after a soak
- Chest pain, shortness of breath or a racing heartbeat that does not settle once you are out of the water
- Very hot skin, vomiting or a severe headache after time in hot water or in the sun
- Someone who went under or inhaled water and is struggling to breathe
- Fever, severe headache and a stiff neck in the days after warm fresh water went up your nose
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What the Coamo hot springs are
The Baños de Coamo are a natural hot spring with soaking pools in the municipality of Coamo, on the south side of Puerto Rico. Puerto Rico’s State Historic Preservation Office places them in the San Ildefonso barrio, and Discover Puerto Rico, the island’s official tourism organization, lists the address as Road 546, km 1.7.
Does Puerto Rico have natural hot springs? Yes. In an April 2026 article published by El Nuevo Día and CienciaPR, hydrogeologist Jobel Villafañe Pagán explains why they surface here: the Great Southern Fault Zone crosses Coamo and branches into smaller faults, and the spring emerges from a fissure at the foot of a hill beside the Coamo River. Rainwater sinks thousands of feet through those cracks, is warmed by the heat of the Earth’s crust and rises again.
The same article notes that other hot springs once existed on the island, in Ponce, Guayama, San Lorenzo and Caguas, but that Coamo’s are the best known and the ones still flowing today. A postcard was already promoting them in 1925.
The site matters to archaeologists too. According to the State Historic Preservation Office, the petroglyphs at the Baños de Coamo were the first reported in Puerto Rico’s history, and they now lie buried under a layer of sediment near the creek that feeds the pools.
How hot is the water at the Coamo hot springs?
The US Geological Survey (USGS) lists the spring as a monitoring site and sampled it between 1960 and 2005. In most of those readings the water came out at 43 °C (about 109 °F), and nearly all of them fell between 40.5 and 43.4 °C (105 to 110 °F).
That is the spring itself, not today’s pools. The temperature in each pool depends on how the water is managed, and we found no recent official measurement, so test the water before you get in. For comparison, the CDC says hot tub water should not be hotter than 104 °F (40 °C).
This is mineral water. In the USGS samples (1960 to 1988) it carried about 1,700 to 1,900 milligrams of dissolved solids per liter, mostly sulfate (around 1,000 mg/L), sodium, calcium and chloride. It is water for soaking, not for drinking.
What do hot springs help with? What the evidence says
Hot springs have been credited for centuries with easing arthritis, circulation problems, skin conditions and much more. The honest answer separates what people feel from what has been shown.
What people feel: some people say they come out relaxed, with less tension. That is real for the person who feels it, and it is reason enough to enjoy a hot soak.
What has been studied: soaking in mineral water as a therapy is called balneotherapy. A 2007 Cochrane review of balneotherapy for osteoarthritis found only seven trials, with 498 patients. It saw signs of less pain and better quality of life with mineral baths compared with no treatment, but concluded that the evidence is weak because the studies were poorly done, and that the positive findings should be viewed with caution. The trials did not even measure side effects.
That review covers osteoarthritis only. Hot springs do not replace your treatment, and we found no solid evidence that they treat conditions such as diabetes, high blood pressure or gout. If you live with a chronic condition, keep taking your medicines and go for what the springs do offer: an hour of rest.
How to soak safely in a hot spring
Hot water raises your body temperature, and in Puerto Rico the day’s heat adds to it. These are the steps that matter:
- Keep soaks short and cool off between them. Get in slowly. If you feel dizzy, nauseated, get a headache or notice your heart racing, get out, find shade and drink water. Know the signs of heat exhaustion and heat stroke.
- Drink water before, during and after. You sweat in hot water even when you don’t notice it; see dehydration.
- No alcohol before or during a soak. The CDC advises against it in hot water, and the US Consumer Product Safety Commission (CPSC) warns that it causes drowsiness and raises the risk of drowning.
- Keep your head above water. Don’t go under, don’t jump in, and don’t let water get up your nose. The CDC gives this advice for all naturally hot water because the ameba Naegleria fowleri lives in warm fresh water and hot springs. Infection is very rare (fewer than 10 cases a year in the United States) but almost always fatal, and it happens when water goes up the nose. You cannot catch it by swallowing water. Don’t stir up the sediment on the bottom either.
- Cover open wounds. The CDC advises staying out of the water with an open cut or wound, especially from surgery or a piercing; if you do go in, cover it completely with a waterproof bandage.
- Watch children the whole time. Heat is more dangerous for young children, according to the CDC. For hot tubs, the CDC says children under 5 should not use them; with water as hot as a thermal spring, apply the same judgment and ask about the site’s rules.
- Walk carefully. Wet surfaces are slippery; wear water shoes.
Talk to your doctor first if you have heart or circulation disease, diabetes, high blood pressure or low blood pressure, or if you take medicines that make you drowsy or affect your blood pressure. The CPSC gives that advice for hot tubs, and it applies just as well here.
If you are pregnant, the American College of Obstetricians and Gynecologists (ACOG) says it is best not to use hot tubs or saunas early in pregnancy, because they raise your core body temperature and that can harm the fetus. The CDC advises talking to a healthcare provider before getting into hot water.
This guide is about thermal water. For rivers and swimming holes elsewhere on the island the main risk is a different one: read about leptospirosis.
Tips for visiting the Baños de Coamo
We could not confirm that the pools are open today. Discover Puerto Rico lists the site as having two thermal pools, opening daily from 6:00 a.m. to 9:00 p.m. and charging a small entrance fee. But other reports from 2025 and 2026 describe the facilities at the site as closed or abandoned, without saying whether that includes the pools, and listings disagree on the hours and the price.
Confirm it is open before you travel. The phone number Discover Puerto Rico lists is 787-825-6668; we could not verify that it still works, and other listings show different numbers. If nobody answers, ask the Municipality of Coamo. When you call, ask about the hours and the entrance fee too. Don’t confuse the pools with the lodging next door, which El Nuevo Día reports has been closed since Hurricane María in 2017.
Looking for another nature day out? Read about El Yunque and Río Grande.
- Go early in the morning or late in the afternoon, when the sun is lower.
- Bring drinking water.
- Pack water shoes, a towel and a dry change of clothes.
- Wear sunscreen and a hat out of the water. If you burn, see our sunburn guide.
- Shower before you get in and don’t swallow the water, as the CDC advises for any pool.
- Keep your medicines with you, not in a hot car.
If you need a doctor during your visit
In an emergency (fainting, chest pain, confusion, a near-drowning), call 911; it works in Puerto Rico just as it does on the mainland. According to federal hospital data, Coamo has no hospital; the nearest emergency rooms are in neighboring towns and are listed in our guide to an online doctor in the south of Puerto Rico.
For anything that is not an emergency, such as a dizzy spell that passed but left you with questions, a sunburn, a rash after soaking, or a question about whether hot water is safe with your medicines, you can book an online visit with Dr. Diana Nieves Castro, a general practice physician licensed in Puerto Rico. We evaluate, diagnose and treat; if appropriate, the doctor prescribes and we send your prescription to your pharmacy.
Online visits are only for people who are physically in Puerto Rico. We send you a secure video link that works on your phone, tablet or computer. Traveling from the mainland? See our doctor for visitors guide.
How we care for you
We evaluate, diagnose and treat; if needed, we give you a lab order for a lab near you.
We see adults and children of all ages. Patients under 21: a parent with patria potestad (parental authority) or a legal guardian is on camera for the whole visit and shows photo ID.
Real-time video visit. We send you a secure video link. It works on your phone, tablet or computer.
If appropriate, the doctor prescribes and we send your prescription to your pharmacy.
You must be physically in Puerto Rico during the visit (visitors, tourists and cruise passengers are welcome).
In an emergency, call 911.
Frequently asked questions
Does Puerto Rico have natural hot springs?
How hot is the water at the Coamo hot springs?
Are the Baños de Coamo open to the public, and what does it cost?
What do hot springs help with?
Are hot springs safe during pregnancy?
Can children go in the hot springs?
Is it safe to put your head under the water?
About this page
Author: The Health Initiative
Medical care provided by Dr. Diana Nieves Castro, MD (PR license 24027)
Disclosure: Founding Executive Director of The Health Initiative
Published: 2026-10-09 · Updated: 2026-10-11
Sources (14)
- Banos de Coamo Spring, Coamo, PR: monitoring location USGS-180219066222500 (US Geological Survey) (opens in a new tab) (accessed 2026-10-09)
- Baños de Coamo (Coamo Hot Springs): address, hours and entrance fee (Discover Puerto Rico) (opens in a new tab) (accessed 2026-10-09)
- Hot springs in Puerto Rico: why do they only flow in Coamo today? (CienciaPR and El Nuevo Día, April 27, 2026) (opens in a new tab) (accessed 2026-10-09)
- Información arqueológica del municipio de Coamo (Puerto Rico State Historic Preservation Office, in Spanish) (opens in a new tab) (accessed 2026-10-09)
- El Nuevo Día, May 31, 2026: report on rebuilding the lodging next door, closed since Hurricane María (in Spanish) (opens in a new tab) (accessed 2026-10-09)
- Balneotherapy for osteoarthritis (Verhagen et al., Cochrane Database of Systematic Reviews, 2007) (opens in a new tab) (accessed 2026-10-09)
- Preventing Naegleria fowleri infection when swimming (CDC) (opens in a new tab) (accessed 2026-10-09)
- About Naegleria fowleri infection (CDC) (opens in a new tab) (accessed 2026-10-09)
- What you can do to stay healthy in hot tubs (CDC) (opens in a new tab) (accessed 2026-10-09)
- Preventing swimming-related illnesses (CDC) (opens in a new tab) (accessed 2026-10-09)
- CPSC Warns Of Hot Tub Temperatures, release 79-071 (US Consumer Product Safety Commission) (opens in a new tab) (accessed 2026-10-09)
- Can I use a sauna or hot tub early in pregnancy? (ACOG) (opens in a new tab) (accessed 2026-10-09)
- Heat and your health (CDC) (opens in a new tab) (accessed 2026-10-09)
- CMS: Hospital General Information (Puerto Rico) (opens in a new tab) (accessed 2026-10-02)