What are the rules for the butterfly in the summer Olympics?

Answer 1

Start:

You must not move on the blocks.

You must not enter the water before the beeper.

Stroke:

Your arms must be sychronised and move together.

Your legs must kick together at the same time.

Your arms must come out of the water behind you, travel across the water and enter it in front of you.

On turns and finishes:

Your hands must touch the wall at the same time.

You cannot do a flip turn/tumble turn.