Drowning

Not all types of drowning are created equally. Even just the difference between salt water and fresh water is extreme. Fresh water can considered as hypotonic to blood and will stream into your blood stream. This results in many consequences besides the whole lungs filled with water and not being able to breathe issue.

Salt water on the other hand is hypertonic to blood, meaning it'll pull blood into your lungs. You'll basically be drowning partially due to your own blood.

Even if you "survive" drowning, you're definitely not safe yet. You could certainly experience what's referred to as dry drowning (or delayed drowning) which is basically your body running out of energy due to the water left in your system from the prior incident. In essence, your body runs out of oxygen and this can be caused by as little as 2 milliliters of water per kg of body weight. You probably won't even show any symptoms beforehand.

This bit of information could very likely save someone's life.