Science of Spearfishing

Spearfishing shows how objects appear to bend when inserted into the water, leading to questions and investigations about light refraction and light polarization.

• When spear fishing, why do you miss when aiming directly at the fish? And why does the angle make a difference?

• Why can you see in the water, and a reflection at the same time?
• Why can you not see what is below the water unless you are close to the water? Or looking straight down?

Students could:

• Start with “spearfishing” in class. This can be done by using a wooden dowel and a fish tank with a target marked on the bottom. Have students make observations as to how they need to aim to hit the target, and how that changes depending on the angle. Have students make observations on the dowel from different sides of the tank. When students look from the side, the target will disappear to them as well.
• Visit a body of water to see if students can see down in the water. Consider taking linear polarizing glasses (or just a filter). This will connect with another phenomenon of polarization. Have students tilt and turn the filter and see how their clarity changes.

• Physics Classroom | Refraction and Sight: This article provides a few more examples of phenomena about light refraction.
• Mammoth Memory | Refraction and Spearing a Fish: This resource provides visual diagrams explaining the concepts behind the spear fishing phenomenon.
• Doctor Eye Health | Polarized VS Non Polarized Sunglasses: This video explains why polarizing filters help to see into the water.
• New World Encyclopedia | Spearfishing: This is an overview of spearfishing, including the history and regulations.