App Store featuring pitch · watchOS + iOS · July 2026
The sensor shows a number.
This app gives it a memory.
Water Temperature turns the depth and temperature sensor in Apple Watch into a living logbook for swimmers, ice bathers and everyone with a favorite lake.
Dive in. That is the whole interaction.
CoreMotion's water submersion APIs launch the app the moment the wrist goes under. The temperature appears live, to a tenth of a degree, with the sensor's own accuracy estimate. Surface briefly and the session waits; leave the water and the dive saves itself, with WeatherKit conditions and an optional place.
The season lives on iPhone
Dives arrive over WatchConnectivity, persist in SwiftData and sync through the user's private iCloud. The logbook grows into statistics, temperature trends and share graphics. Milestones celebrate a first dive, a new coldest record or a new body of water. No streaks, no guilt.
Built on the newest platform capabilities
Every framework earns its place with a visible user benefit.
Auto-launch on submersion, live temperature, depth and Water Lock handling.
Keeps measuring through a whole swim, with a grace period for surfacing.
Attaches the conditions above the surface to every dive.
Saves dives to Apple Health and imports swim workouts, both opt-in.
The logbook syncs privately through the user's own iCloud. No servers.
Dives appear on iPhone moments after surfacing.
Complications plus Home and Lock Screen widgets with the last reading.
Temperature profile of each dive and season trends.
Shader-driven water that shifts from icy blue to warm turquoise with the real temperature.
Why I built it
I have been building apps as an indie developer for ten years. Every summer I drive to a lake in Austria, and every year I wished for exactly this app: one that knows how warm my lake is today and remembers how it felt last July.
So I built it myself, with love for detail and playful animations. The water on screen moves and changes color with the real temperature, and if you watch closely, a small creature sometimes swims by.
