Where does swimming training take place?

Trainings take place on land and in water. While explaining the technical elements, the trainer is in the water and shows how to do the exercises correctly. We tested different training models and realized that learning proper swimming is most effective and efficient when the coach sees your movements under water and above the water + gives immediate feedback, so the coach is in the water (while learning new elements) and then goes to side to control the correctness of the exercise.