(Image credit: Apple)

Apple just announced the Apple Watch Ultra 4 alongside the Apple Watch Series 12, iPhone Duo, and iPhone 18 Pro at the September 9th "Surprise and Shine" event in Cupertino, California.Boasting loads of new wellness tools, improved heart rate tracking, better battery life, an upgraded processor, and a handful of cool AI features, here's everything you need to know about the Apple Watch Ultra 4.Apple Watch Ultra 4: Upgrades cheat sheetPrice and release: The Apple Watch Ultra 4 is available for preorder starting today and will be available on September 18; the price is $799, the same as the Ultra 3Design: The Apple Watch Ultra 4 looks similar to its predecessor; available in Black or Natural TitaniumHealth features: Updated health sensing system; improved heart rate and heart rate variability (HRV) tracking; HRV reflected in Vitals app; new Readiness metric; new Health Age score; redesigned Health app with improved recovery insights and personalized AI health/fitness guidance that updates dynamically; Health app now supports personal health data and lab resultsAI features: Support for Siri AI voice assistant; Live Rewind lets you ‘go back in time’ up to 15 seconds; Sound Recognition can auto-alert users to common sounds like sirens and alarms; Siri Recap takes high-level notes of conversations and generates summariesUnder-the-hood: Upgraded S11 processorBattery life: Improved battery performance lasts up to 48 hours per charge; up to 18 hours when recording a workout with heart rate and GPS trackingThe Apple Watch Ultra 4 is a substantial upgrade over the Apple Watch Ultra 3, which is currently one of the best smartwatches you can buy.Apple Watch Ultra 4: Price and availability