The Garmin quatix 8 (51mm) is the larger, longer-battery-life version of Garmin's marine smartwatch, sharing core hardware with the fenix 8 51mm but adding deep integration with Garmin's boating electronics — this AU/NZ/AFR Sapphire edition suits boat owners and sailors who want maximum time on the water between charges. It uses a 1.4" AMOLED touchscreen at 454 x 454 resolution under a scratch-resistant sapphire lens, in a titanium-bezelled case dive-rated to 10 ATM (40m) with leakproof buttons and a metal sensor guard. Marine features include remote control of compatible Garmin trolling motors and Fusion entertainment systems, live water depth/speed/heading and wind readouts, tide change and anchor drag alerts, tack assist, race start guidance and a regatta timer, alongside preloaded boating and sailing apps. It also carries dual-frequency multi-band GPS, the Elevate Gen 5 heart rate sensor with ECG, Pulse Ox, a built-in speaker and microphone for calls, Garmin Pay, and Garmin's usual training/recovery metrics for use on land. Battery life runs up to 29 days in smartwatch mode and, based on shared fenix 8 51mm hardware, roughly 84 hours in GPS-only mode — substantially longer than the 47mm quatix 8. Choose this size if you want the longest possible time between charges on extended trips.