Why does a swimming pool have to have deep water?

Q: Why does a swimming pool have to have deep water?

Before the pool is constructed, the pool company's people will plan the location of the deep water area in advance of the design, so why is it important to have a deep water area for the pool?

echo: In fact, whether it is deep water or shallow water, the buoyancy is the same when a person is swimming, the buoyancy does not change, but the drag decreases.
While it's true that buoyancy doesn't change, resistance decreases, specifically the water waves created by the water travel down to the bottom of the pool and reflect back up, creating resistance to the person, and the deeper the water, the less resistance is reflected back up for a longer period of time.
Overall, resistance while swimming comes from three main sources:

1、Shape resistance
It is also the resistance caused by the shape of the person, so the body posture is emphasized in swimming instruction, and the instructors are asking the students to keep their bodies as straight as possible to reduce the cross-section area and thus reduce the shape resistance.
You can simply do a small experiment to experience: palms perpendicular to the water surface, push the water forward; as well as palms flat, parallel to the water surface, push the water forward. Definitely the former is laborious, is because the cross-section area is large, the shape of the resistance is large, so it will feel more laborious.

2,surface resistance

This is something that the average person may experience less because it is so common, mainly in the resistance generated by the friction between the surface of the object (the swimmer) and the water, and generally the smoother the resistance, the lower it will be; the average person should be pretty much the same.

3、Water wave resistance

As the name suggests is the resistance caused by water waves to people, in short, we usually watch swimming to see the splash, the splash is big, the resistance is also big, the faster the speed, the water waves will also be bigger, the resistance will also become bigger. This is also the reason for setting up a deep pool.
The deeper the water, the less perturbation will be reflected back, and the less wave resistance there will be. In addition the depth of the water makes it easier for the athlete to circumvent the wave resistance by diving (as there will be less wave resistance underwater than at the surface).

That's why the standard pools for international competitions are now reaching the3The reason for the meter water depth.