I've been training on a 'race board' (as they're called in Australia; also known as a paddleboard (not a stand-up paddleboard) or sometimes rescue board) - it's like a surfboard, but narrower and more buoyant, and they're used in races/competitions often by lifesaving clubs. The motion is much like paddling when you're surfing, but the surfing part is usually only when you're going back into shore; it's the paddling (with your arms) that the activity is about (there's also an up-on-your knees, paddling with both hands motion. I can't find or think of what the best activity type on my Fenix is to track this - surfing only wants to track the waves you've caught, but is the closest in a physical sense, while kayaking or SUP tracks the path/distance, but the motion is completely different, so stats (distance per stroke) might be out.
Anyone have any ideas? I have no idea if this is a predominantly Australian sport, and its kind of hard to search for it as SUP seems to get all the hits these days.