In the swimming competition, what kind of swimming posture can be at the start and turns, a swimmer is permitted one or more leg kicks and one arm pull under the water, which must bring him to the surface? It shall be permissible for a swimmer to be completely submerged for a distance of not more than 15 meters after the start and after each turn. When by that point, the head must have broken the surface. The swimmer must remain on the surface until the next turn or finish.