Hi
When recording specific fitness activities, be sure to use the Workout app and to choose the activity type that most closely matches your workout.
This enables your watch to use the most appropriate sensors and data sources when tracking results.
Choose Other for any workouts that are neither included within nor sufficiently similar to those in the main list, including for canoeing.
When recording an Other workout, the Workout app will credit one minute of Exercise for each full minute of the workout. Active calories will be estimated at a rate equivalent to a brisk walk or based on data recorded by the heart rate sensor, whichever is higher. Note that neither distance (for any workouts) nor a route map (for outdoor workouts) are recorded under this workout activity type.
Upon ending the workout, tap on the option to Name Workout. Available labels include, for example, Paddling.
"Other" workouts that have previously been named will become available to repeat within the Workout app, complete with their previously selected naming label.
If you would like to submit a feature request for Canoeing to be added as a main activity type, complete with distance tracking, route map and custom estimations for active calories, then you can do so here:
Feedback - Apple Watch - Apple
More information:
Work out with your Apple Watch - Apple Support
Get the most accurate measurements using your Apple Watch - Apple Support
Use the Activity app on your Apple Watch - Apple Support
Your heart rate. What it means, and where on Apple Watch you’ll find it. - Apple Support