7

The easy technique is to simply hold the spear in your hand with the tip under the water and stab the fish. Once your spear enters the water, refraction has identical effects on your view of the spear point and your view of the fish, so you can easily guide it to where you want. Throwing a spear to hit a fish takes a great deal of practice. The physics of ...


5

I keep the snorkel in my mouth during 'duck dives'. When nearing the surface, I look upwards - that makes the snorkel point downwards, and just a small trickle of air can purge it, since the air is 'trapped' inside the downwards-pointing snorkel. Just when surfacing, tip the head, so you are looking downwards again (the timing may take a little practise) - ...


2

The math is trigonometry but I think you would need to get a feel. It is not like you could run the math on the fly anyway. The ratio of sin above and the sin below is 1.33. More angle is more bend. At perpendicular there is zero bend. At 45 about 13 degree of bend. At 45 degrees if the fish looked like a depth of 2' you would need to aim like 7" ...


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