You asked, and we listened! Swim.com for the Apple Watch now has a drill mode and pace timer!
Using both functions starts with the watch’s digital crown. To start setup for the drill mode, you’ll scroll the digital crown upwards. To start setup for your pace (or send-off) timer, scroll downwards.
You can start setup for your drill at anytime the watch says “Resting” in red letters. This may be at the beginning of your workout or anytime you’re resting at the wall. While in rest mode, scroll the digital crown on the side of the watch upward until the drill mode menu appears. Here you can set the distance for your drill using the plus and minus buttons. When you’ve set the distance, scroll up to start the drill mode. When you are done with the drill, you can scroll up again to start a new drill interval, or scroll down to return to your main swim stroke mode. Once you scroll down your drill distance will be added to your total. Drill mode should retain the last distance setting you used during the workout.
To set up your pace timer, from resting mode scroll the digital crown button down to expose the timer. Use the plus and minus buttons to adjust your time.
When you are finished setting the timer, scroll up to start it immediately You can also scroll the crown button down to exit if you are not ready to use it yet. If you choose to not use it immediately, you can scroll down during any resting period at the wall to open the pace/send-off menu again, and then scroll up to begin the timer.
When the timer runs out, you should feel a small vibration to alert you.