You can use your Suunto 9 for swimming in pools or openwater.
When you use a pool swimming sport mode, the watch relies on the pool length to determine distance. You can change the pool length as needed under the sport mode options before you start swimming
Openwater swimming relies on GPS to calculate distance. Because GPS signals do not travel under water, the watch needs to come out of the water periodically, such as with the freestyle stroke, to get a GPS fix.
These are challenging conditions for GPS, so it is important that you have a strong GPS signal before you jump in the water. To ensure good GPS, you should: