Marine Metrics

A tides and water temperature app for anywhere in the world.

What Inspired Me

I live right next to the sea, and one of my favourite routines is walking my dogs when the tide is high. I've also always been fascinated by tides, so Marine Metrics started as a way to scratch my own itch: a simple, clear app that tells me what the water is doing and how warm it is, wherever I am.

I quickly realised it wasn't just useful for me. Sailors, fishermen, swimmers, surfers, and everyday coastal walkers all make decisions based on the sea, so I built the app for anyone who interacts with it.

What I Learned

Building Marine Metrics solo over about a month taught me far more than I expected.

• Backend architecture: The biggest technical lesson was designing a backend that sources tide and water temperature data from multiple APIs, mixing local and global sources so the app works wherever you are on Earth.
• Securing a paid API without logins: Some of the data comes from a paid API, and I didn't want to force users to create accounts. I learned to use Apple's App Attest to verify that requests genuinely come from my app, without traditional authentication.
• How tides actually work: I learned what causes tides, and that most tide timings are estimates derived from buoy readings combined with an offset based on the moon's position.
• Designing with new tools: It was my first time using Google Stitch, which I used to generate the initial design before iterating on it by hand.

How I Built It

I built the app in Xcode using SwiftUI, with Supabase powering the backend. The backend pulls from multiple APIs to deliver either local or worldwide tide information, depending on where the user is.

I'm proudest of the landing screen. Everything is laid out clearly, so the key information is obvious at a glance.

Challenges I Faced

• Pulling together accurate, consistent data from several different sources.
• Securing a paid API without a login system.
• Turning complex ocean data into something simple enough to read in a second.

What's Next

The name Marine Metrics is deliberately broad. I plan to widen the app's reach with additional data such as solunar tables, so it becomes a one-stop companion for anyone who spends time by the water.

Built With

• api
• supabase
• swiftui
• xcode