The rugged Forerunner 310XT is the triathlete's indispensable training tool; a GPS-enabled, swim-proof trainer that tracks bike and run data andsends it wirelessly to your computer

Features include

Four customisable data screens
    Syncs with foot pod for accurate date, even on a tread mill
    Programmable to record transition times, and auto change between activities
    Compatible with all ANT+ power meters
    Waterproof to 50 m
    20 hour battery life

Tri247 says: If you want the cleverest sports watch out there bar none then it's currently the Forerunner 310XT.