Why does an observer looking down at the water seem to be less deep than it really is? How deep will the river appear if in reality it is 2 m?

The virtual bottom image is higher than the real one. 1.5 m.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.