Overview
People float high in the Dead Sea because the water is unusually dense. Its brine contains about 34.2 percent dissolved salts, roughly ten times ocean salinity. A given volume of brine weighs more than the same volume of fresh water, so it produces a stronger buoyant force.
Most people still need to keep control of their position. High buoyancy does not remove the risk of turning face-down, getting brine in the eyes or mouth, or losing balance at the shoreline. The science and the safety rules belong together.
Density makes the difference
Water pushes upward on any object placed in it. Whether the object sinks, stays suspended or floats depends largely on the relationship between the object’s average density and the fluid’s density.
Fresh water has a density close to 1.00 gram per cubic centimetre. Measurements of Dead Sea brine are about 1.24 grams per cubic centimetre at 25 degrees Celsius; the exact value changes with temperature and the sampled water, but the contrast is large enough to explain the distinctive floating experience.
A person’s average density also varies with body composition and the amount of air in the lungs. In ordinary water, many people float with much of the body submerged. In denser Dead Sea brine, less of the body needs to sit below the surface before the upward force balances the person’s weight.
Floating is not caused by a mysterious mineral effect on the body. It follows from density. Dead Sea brine weighs substantially more per unit of volume than fresh water, so a smaller submerged portion of the body can displace enough liquid to balance the body’s weight.
For more background, see how Dead Sea salinity is measured.
The Dead Sea and ocean comparison shows how the two waters differ.
Archimedes’ principle in the Dead Sea
Archimedes’ principle states that an object in a fluid experiences an upward buoyant force equal to the weight of the fluid it displaces. A floating object settles at the point where that upward force balances its weight.
Imagine that two equal containers are filled, one with fresh water and one with Dead Sea brine. Dissolved salts make the brine heavier. A body therefore needs to displace less Dead Sea water than fresh water to receive the same upward force.
This is why a person’s legs and torso tend to sit higher at the surface and why conventional face-down swimming is a poor fit for the setting: the water resists submersion, while the consequences of splashing concentrated brine into the face are serious. The safer experience is controlled, face-up floating at a permitted beach under lifeguard supervision.
Why is the Dead Sea water so dense?
The Dead Sea is a terminal lake, which means water enters the basin but does not flow out through a river to the sea. Water leaves mainly through evaporation, while much of the dissolved material remains. Over time, the lake developed a very high concentration of salts.
Its chemistry is not simply ocean water with extra table salt; Dead Sea brine contains substantial magnesium, calcium, potassium, sodium and chloride ions. That composition affects density and gives the water different physical properties from ordinary seawater. The guide to Dead Sea depth and dimensions explains the basin, while where the Dead Sea is located places it within the rift valley.
The Dead Sea behaves like any other fluid under Archimedes’ principle. What makes the result unusual is the brine’s density; the law of buoyancy is ordinary, while the concentration of dissolved salts is extraordinary. That difference moves a larger share of the body above the surface.
Does everyone float in the Dead Sea?
Most people are markedly more buoyant in the Dead Sea than in fresh water. The exact position of a body at the surface varies with body composition, lung volume, clothing, movement and water conditions. It is therefore better to say that Dead Sea brine makes floating much easier, rather than promise that every person will float in exactly the same way.
Swimming ability is not a substitute for caution. A strong swimmer can still be harmed by brine in the eyes or mouth. Children require constant close supervision because they may not be able to recover their position calmly. Israel’s Ministry of Health advises an adult supervising a young child around water to remain within touching distance and give constant attention.
How to float safely
Enter only at a permitted bathing beach when a lifeguard is on duty. Follow the lifeguard’s directions and the posted conditions, since the safe entry point can change. Move slowly on the shore and in shallow water, where salt deposits or uneven ground may make footing difficult.
Keep the face, eyes and mouth out of the water; do not swallow the brine and do not go far from shore. Avoid splashing, diving or trying to swim face-down. If water enters the eyes or mouth, leave the water and seek help from the lifeguard or beach staff.
There is no single time limit that suits every visitor. Health, weather and beach conditions differ. Follow the instructions at the supervised beach, leave the water if you feel unwell, and consider medical advice before entering if a health condition affects your safety around water.
Before visiting, read the full Dead Sea swimming safety rules.
The eye-safety page explains how to protect your eyes from salt water.
Check the separate advice about cuts and wounds before entering.
The step-by-step guide to floating in the Dead Sea can help you plan the experience.
Frequently asked questions
What percentage of salt is in the Dead Sea?
Dead Sea brine is about 34.2 percent dissolved salts, compared with an ocean average of about 3.5 percent. Salinity can vary by sampling location and method, so the number is best understood as a representative value. The lake’s ionic composition also differs from that of normal ocean water.
How dense is Dead Sea water?
Scientific measurements place Dead Sea brine near 1.24 grams per cubic centimetre at 25 degrees Celsius, compared with about 1.00 for fresh water. Density changes with temperature and composition. That large difference is enough to make a person sit higher in the water than in an ordinary pool.
Can you sink in the Dead Sea?
The dense brine makes most people highly buoyant, but “you cannot sink” is not a useful safety promise; a person can lose postural control, turn face-down or encounter difficulty at the shore. Stay in the permitted bathing area, keep your face up and follow the lifeguard’s instructions.
Do you need to know how to swim?
Dead Sea brine can support a person more readily than fresh water, but water confidence and supervision still matter. Do not test the lake alone or outside a permitted beach. Children and anyone uncomfortable in water need close assistance, even when buoyancy makes floating feel easy.
Why should you not swim face-down?
Face-down swimming makes it easier for concentrated brine to enter the eyes, nose or mouth; the water’s density can also make ordinary strokes and changes of position awkward. Controlled face-up floating, close to shore and under active lifeguard supervision, keeps the main hazard away from the face.
