That depends on what you need.
There has been a recent boom of wearable technology for swimmers, each gadget making claims of its own. From splits to stroke identification you can find a watch, a band or even a pair of goggles to measure whatever you want, but of course the obvious question remains: how good are they really?
Is the TritonWear® device a valid measurement of swimming performance
Twenty youth swimmers completed a 100 m swim in a 25 m pool, swimming breaststroke or freestyle wearing the TritonWear® device, whilst being filmed above and below water with three cameras.
The TritonWear® can be used for basic metrics of performance, such as split-time and speed but the error of more complex measurements, such as time underwater or turn-times, renders them unable to identify typical performance changes.