Apple Watch Series 2: Processor & Fitness tracking

Under the hood, there's a new second generation dual-core S2 chip processor that's 50% faster than the one inside the Apple Watch, while a new GPU offers twice the graphics performance.

Apple is also packing the new S2 processor into the Apple Watch Series 1, so you can benefit from the speedier performance there as well.

Apple Watch Series 2: Fitness tracking

It's fair to say the sports credentials of the first Apple Watch were not quite up to scratch. The general fitness tracking was great, but the lack of GPS and some questionable heart rate data meant it was far from a sports watch killer.

Now Apple has sought to make the Series 2 a more formidable Garmin and Polar rival by adding built-in GPS so you can now go running sans iPhone. This will work with walking and cycling as well, recording distance, pace and speed metrics.

There's also swim tracking on board, for open and pool water swimming, letting you count laps, track average lap pace and auto-detect stroke type.

You get the same heart rate sensor here as the first Watch, to continuously measure heart rate during a workout and throughout the day with the data being fed into Apple Health and third-party health and fitness apps.