@freeheeler I can answer that, it’s called drill mode, once you enable it, you get another screen where every time you reach the end of pool, you manually press a button to add 25 meters and so forth.
Once you’re done with legs only or any other type of technique specific swim where hands don’t move at all, you disable it, you’re back to your normal swim screen. The distance swam under this mode gets appended to your total distance of that swim session.
This feature has been missing pretty much since the S line of Suunto watches. However it’s a core feature of any swim training, most pool swimmers won’t skip this, only the Suunto watches do 😉