How do I reset the length of a pool on my iWatch?

Start a workout

You can use these steps to start a workout or ask Siri. For example, say "Hey Siri, start a 30-minute indoor run."

1. Open the Workout app.
2. Scroll to see your options, then tap a workout or tap Other. Choose the one that best matches what you’re doing.
3. Swipe left or right to set a calorie, distance, or time goal. To skip setting a goal, choose Open.
   • To change between miles or kilometers, firmly press the distance goal screen.
   • To change between calories and kilojoules, firmly press the calorie goal screen.
   • To change between yards and meters while swimming,1 firmly press the distance goal screen or the pool length screen.

Swim

With Apple Watch Series 2,1 there are two swimming workouts: Pool Swim and Open Water Swim. For Pool Swim, be sure to accurately set the pool length to help your Apple Watch measure laps and distance. When the workout starts, the screen automatically locks to prevent accidental taps. To unlock the screen, pause your workout by pressing the side button and Digital Crown at the same time, then turn the Digital Crown. To resume, press both buttons again.

To end your workout:

1. Press the Digital Crown and the side button at the same time to pause your workout.
2. Dry your screen. If the screen's wet, the water might cause accidental taps.
3. Turn the Digital Crown to unlock the screen and clear any water from your Apple Watch. Your watch makes a sound, and you might feel water on your wrist.
4. Swipe right and tap End.

When in a Pool Swim or Open Water Swim in the Workout app, water may prevent a heart rate measurement, but Apple Watch will still track your calories using the built-in accelerometer. Learn more about the accuracy and limitations of the heart rate sensor. During an Open Water Swim where you use a freestyle stroke, your Apple Watch will also use GPS to measure pace and distance.

Enjoy your swim!