Drowning in fresh water is different from drowning in salt water. For a person, more people are drowning in fresh water than in salt water. About 90% of the drowning occurs in fresh water, including swimming pools, bathtubs and rivers. This is partly due to the chemical nature of the water and how it affects penetration. Drowning involves suffocating in the water. You don’t even need to breathe in the water, but if you inhale salt water, high salt concentrations will prevent water from entering your lung tissue. When people are submerged in salt water, it is usually because they cannot absorb oxygen or emit carbon dioxide. Breathing in saline creates a physical barrier between the air and the lungs. People who inhale salt water will not be able to breathe again before removing salt water. However, this does not mean that there will be no lingering effects. The concentration of ions in the lung cells is hypertonic, so if swallowed, the water in the blood will enter the lungs to compensate for the difference in concentration. This can cause your blood to thicken and put pressure on your circulatory system. Extreme stress on the heart can cause cardiac arrest within 8 to 10 minutes. The good news is that it’s relatively easy to replenish blood through drinking water, so if you survive the initial experience, you can recover. Surprisingly, even if you avoid drowning, you may die from breathing fresh water. This is because fresh water is more “dilute” than the liquid in the lung cells relative to the ions. Fresh water does not enter your skin cells, because keratin basically makes them waterproof, but water can pour into unprotected lung cells, trying to balance the concentration gradient on the cell membrane. This can cause a lot of tissue damage, so even if water is drained from the lungs, it may not recover.