Pairs with chloride to make a spring "saline."
Sodium is an alkali metal and the partner of chloride in saline springs. In hot springs it also appears with bicarbonate. It is one of the most common dissolved ions in geothermal water.
Sodium varies from a few mg/L to over 1,000 mg/L in highly saline springs. Sodium-chloride (saline) springs are among the most traditional in balneotherapy.
Saline and mineral-water bathing have a long balneological tradition, and systematic reviews find balneotherapy may be associated with improvement in some rheumatological conditions, with caveats about evidence quality (PMC7383020; PubMed 19570124).
Evidence specific to sodium dermal absorption is limited. Most sodium-related balneology research is really about saline mineral-water bathing broadly, not sodium alone. No clinical evidence shows that sodium in soaking water confers a distinct health benefit beyond the general effects of mineral bathing.
Very saline water can sting broken skin and dry the skin. Rinse after soaking. Sodium in soaking water is irrelevant to dietary sodium intake.
181 springs with verified sodium data · showing top 50 · source: USGS Water Quality Portal
Squaw Hot Springs
id · 102°F · primitive
4300 mg/L
Battle Creek Hot Springs
id · 102°F · primitive
3100 mg/L
Brockman Creek Hot Spring
id · 102°F · primitive
2100 mg/L
Heise Hot Springs
id · 102°F · developed
1500 mg/L
Alpine Warm Spring
id · 85°F · primitive
1500 mg/L
Malad Warm Spring
id · 90°F · primitive
1200 mg/L
Prices Warm Spring
id · 85°F · primitive
1200 mg/L
Woodruff Hot Spring
id · 102°F · primitive
910 mg/L
The Landusky Plunge
mt · 77°F · primitive
760 mg/L
BLM Well (Frazier Hot Spring)
id · 105°F · primitive
510 mg/L
Maple Grove Hot Springs
id · 102°F · primitive
490 mg/L
White Licks Hot Spring
id · 102°F · primitive
420 mg/L
Cove Creek Hot Spring
id · 102°F · primitive
320 mg/L
Crane Creek Hot Springs
id · 102°F · primitive
280 mg/L
Pleasantview Warm Springs
id · 85°F · primitive
280 mg/L
Sharkey Hot Spring
mt · 102°F · primitive
270 mg/L
Grape Creek Warm Spring
id · 85°F · primitive
240 mg/L
Big Creek Hot Springs
mt · 102°F · primitive
220 mg/L
Hot Springs State Park
wy · 104°F · primitive
210 mg/L
Cleveland Hot Springs
id · 102°F · primitive
208 mg/L
Lakey Hot Spring
id · 102°F · primitive
200 mg/L
Bear Lake Hot Springs
id · 102°F · developed
180 mg/L
Lava Hot Springs
id · 130°F · developed
170 mg/L
Sullivan Hot Springs
id · 102°F · primitive
170 mg/L
Roystone Hot Springs
id · 105°F · developed
160 mg/L
Rock Creek Hot Springs
mt · 112°F · primitive
160 mg/L
Riggins Hot Springs
id · 102°F · primitive
160 mg/L
Beardsley Hot Springs
id · 102°F · primitive
150 mg/L
Salmon Falls Hot Spring
id · 102°F · primitive
140 mg/L
Hot Sulphur (Miracle Hot) Springs
id · 102°F · primitive
130 mg/L
Krigbaum Hot Springs
id · 102°F · primitive
130 mg/L
Stinky Warm Spring
id · 85°F · primitive
130 mg/L
Kwiskwis Hot Spring
id · 102°F · primitive
120 mg/L
Boulder Creek Spring
id · 102°F · primitive
120 mg/L
Indian Creek Hot Spring
id · 102°F · primitive
110 mg/L
Barrons Hot Spring
id · 102°F · primitive
110 mg/L
Middle Fork Indian Creek Hot Spring
id · 102°F · primitive
110 mg/L
Cabarton Hot Spring
id · 102°F · primitive
110 mg/L
Indian Springs (Resort)
id · 102°F · developed
110 mg/L
West Pass Hot Spring
id · 102°F · primitive
110 mg/L
Boulder Hot Springs
mt · 102°F · resort
110 mg/L
Sunflower Flat Hot Spring
id · 102°F · primitive
97 mg/L
Rocky Canyon Hot Springs
id · 102°F · primitive
97 mg/L
Starkey Hot Springs
id · 102°F · primitive
96 mg/L
Firehole Lake
wy · 160°F · developed
95 mg/L
White Arrow Hot Spring
id · 102°F · primitive
94 mg/L
Lower Loon Creek Hot Spring
id · 102°F · primitive
94 mg/L
Cox Hot Springs
id · 102°F · primitive
93 mg/L
Elk Creek Hot Spring
id · 102°F · primitive
92 mg/L
Warm Springs Creek Hot Springs
id · 102°F · primitive
90 mg/L