The Garmin Forerunner 235 is basically an outdoor running watch with GPS but is not purposely designed for swimming. However, up to 50m waterproofing feature is offered just like on most GPS watches these days. So, you can wear Garmin Forerunner 235 Waterproof during water based activity and swimming. The Garmin Swim is one of the swim watches and triathlon watches with specific swimming activity section so it comes with stroke pace and efficiency and other recording of particular swim metric data. But you can use the Other Activity section for swimming when using the 235. Already pre-programmed into the watch are running and cycling.
Garmin Forerunner 235 Waterproof: Pool Swimming
You can track your progress and distance using the GPS capabilities of the watch when swimming in open water. However, you may not need the GPS function as you will most likely use a lapped pool to swim indoors. So, you want the lengths and number of laps completed and lap/ length time displayed on the watch’s Activity settings by editing the data screens. Knowing the amount of lengths you had completed would easily allow you to calculate the total elapsed distance and the length of the pool.
Garmin Forerunner 235 Waterproof: Open Water Swimming
There is a variety of triathlon watches which are designed to be used for outdoor swimming in open lakes or the sea such as the Forerunner 735XT that feature the specific Open Water Swim mode to track stroke type alongside the GPS and the internal accelerometer. Unfortunately, the Garmin Forerunner 235 Waterproof has no Swim option and the capabilities in open water. The main issue of using the Forerunner 235 for open water swimming is incorrect distances recorded as the route taken is not in the straight path and often meander in nature which the watch would always be used on land.
The issue of all running and triathlon watches is in the software side not the type of GPS hardware system when using GPS data for swimming. There are constant changes in GPS signal strength when in open water swimming so Garmin triathlon watches come with special algorithms encoding for underwater. When open water swimming, these algorithms can evaluate and correct this issue. Generally, the Forerunner 235 is not designed for swimming, but most amateur and leisure swimmers would find it is completely competent of meeting many of their needs. The Garmin Forerunner 235 Waterproof would give you the best results.