Garmin Fenix 9 wins on battery life (14 days vs 36 hours per manufacturer data) and multi-sport depth, beating Apple Watch Ultra 3 by 2 points in performance and longevity. Apple Watch Ultra 3 excels in iOS integration and display quality but trails on endurance metrics. RTINGS and CNET reviews highlight Fenix 9's navigation edge for hikers while noting Ultra 3's dive rating advantage.