Overall, I really want to love my Garmin Descent Mk3i. As a tool for diving and fitness, it's nearly perfect. The GPS is lightning-fast, the build quality is exceptional, and the battery life truly lives up to the hype. It feels like a rugged, capable companion for adventures.\r\n\r\nHowever, for a watch in this premium price range, I have one significant gripe that holds me back from giving a full five stars: the sleep tracking is surprisingly inconsistent.\r\n\r\nThe core of the issue isn't that it doesn't track sleep at all, but that it often does so inaaccurately and at the wrong times. For instance:\r\n\r\n· If I'm relaxing on the couch in the evening, being still while watching a movie or reading, the watch sometimes interprets this lack of movement as me being asleep. This leads to the "sleep" data starting far earlier than it actually does.\r\n· Conversely, on nights when I lie awake for a while, it doesn't always seem to capture that period of restlessness correctly.\r\n\r\nThe other minor frustration is the somewhat rigid "Sleep Mode" schedule. While I understand the intent is to help with sleep hygiene, I wish it were more of a suggestion than a default. For those of us with irregular schedules, the automatic dimming and Do Not Disturb activation can be a nuisance if you're still active, and while you can adjust the times, you can't easily completely decouple it from the sleep schedule without manual intervention.\r\n\r\nThe Bottom Line: This is a phenomenal diving and sports watch that feels let down by its sleep tracking features. If your primary focus is on underwater performance, surface activities, and navigation, the Mk3i is arguably one of the best you can buy. But if nuanced, granular sleep analysis is a top priority for you, this might not be the device to meet that specific need. It's a fantastic tool that's unfortunately just okay at tracking rest.