How you draw someone swimming and diving depends on what you are going to use the drawing for. If it is for an art display, then you want to use your creativity to make the picture as interesting and engaging as possible. Since art is such a personal and indefinable thing, how your picture will come out depends on your interpretation and your skills at drawing. If you are just looking for a basic representational image of the swimming and diving then you could just use a stick person and use triangles for flippers if you mean scuba diving or you can add a diving board if you are talking about high diving.
Remember when you are drawing someone swimming you should have them horizontal and it helps to show the top of the water with maybe fish, dolphins or jelly fish floating past to give context.
Remember when you are drawing someone swimming you should have them horizontal and it helps to show the top of the water with maybe fish, dolphins or jelly fish floating past to give context.