What are the butterfly rules?

Under Article 101.3 (as amended for 2026):

• Start: forward start.
• After the start and each turn: the body must be on the breast. Any number of kicks is allowed, but only one arm pull underwater, which must bring the swimmer to the surface. The swimmer may be fully submerged for up to 15 meters. By then the head must have broken the surface, and the swimmer must stay on the surface until the next turn or finish.
• Arms: brought forward together over the water and pulled back together under the water for the whole race.
• Kick: all up and down leg movements must be simultaneous. The legs needn't be level, but they can't alternate. No scissor or breaststroke kick.
• Turns: body on the breast, and a two-hand touch, separated and simultaneous, at, above or below the surface. After the touch the swimmer may turn any way, but must be on the breast when leaving the wall.
• Finish: on the breast, with a separated, simultaneous two-hand touch. New: once some part of the head has passed the final 5-meter or 5-yard mark before reaching for the finish, the swimmer may be completely submerged.