For those that are not familiar with the sport of free-dive spearfishing, it entails using a breath-hold technique and swimming down to your target depth where you would then shoot a fish using an elastic band-powered spear gun.
This is a dangerous sport for several reasons. Using a breath-hold technique is dangerous because as you begin to push your limits in depth, you run the risk of losing consciousness due to lack of oxygen to the brain. Once a person is unconscious, their autonomic nervous system kicks in and the brain tells the lungs to breathe, causing that person to draw in a lung full of water and drown. Another element of danger associated with this sport is the presence of predators such as sharks. When you are successful in swimming down, finding a fish and shooting it with your spear gun, getting blood in the water is unavoidable. Predators of the sea, like sharks are attracted to blood and some say they can smell a single drop from a mile away. The blood in the water can not only attract them but also put them in a feeding frenzy with aggressive behavior. For a free-dive spear-fisherman, seeing and dealing with sharks is almost guaranteed. It's not if, it's when.
All danger aside, free dive spearfishing provides you with a pure, euphoric adrenaline rush. From the moment you enter the water, you've left your natural environment and entered an alien domain where everything is faster, more agile, and more attuned to the environment around them. This inferior feeling is humbling as you swim down into the blue abyss. A very caveman-esque adrenaline rush washes over you as you swim down with just you and your spear gun, looking for prey and jumping another predator does not materialize out of the blue.
When descending, sometimes there is what is called a thermocline. This is a layer of water with a warmer temperature and heavy salinity levels, causing it to be extremely blurry and not concufficient to good visibility. Immediately below the thermocline the water becomes noticeably colder and visibility is greatly improved. Breaking through the thermocline is always an intense moment, one second you're surrounded by this blurry water and can hardly see your hand in front of your face and the next moment it's like a veil has been lifted and you can see clearly all around you .
When one finally reaches the bottom or their target depth, chooses which fish they want to harvest, makes the kill shot, and propels themselves back the surface, the feeling of success and accomplishment is incomparable.