Ocean Depth Map privacy policy

Effective November 13, 2026

Ocean Depth Map is a free app for iPhone and Android and a web app at depth.hertzmc.com that shows the approximate water depth under your position on a depth chart. It's made by Jayden Hertz. This page explains exactly what leaves your phone.

Your location

• The app uses your location only while it's open on your screen, to show where you are and the depth under you.
• The depth is worked out on your phone (or in your browser) from depth tiles it has downloaded. Your position is never sent to us or to anyone else, and it is never stored. The app doesn't track you in the background.

What the map downloads

Like any map, the app downloads small map pictures (tiles) for the part of the world you're looking at. Each request shows the server which area you are viewing (not your exact position) and, like any internet request, your IP address:

• Depth tiles come from our own server, depth.hertzmc.com (delivered by Cloudflare). We don't store these requests.
• Place names, roads and borders come from OpenFreeMap (tiles.openfreemap.org), a free map service. See OpenFreeMap's privacy policy.
• The NOAA chart, only if you switch it on, comes from NOAA's chart server (gis.charttools.noaa.gov), a US government service. See NOAA's privacy policy.

What's saved on your phone

Map tiles you viewed or saved for offline use, your units, your layer choice and the last map view are kept only on your phone or in your browser. We never receive them. Uninstalling the app (or clearing the site's data in your browser) deletes them. The Android app doesn't copy anything to a Google backup.

App updates

When the iPhone or Android app opens, it checks Expo's update service (expo.dev) for small fixes, so they arrive without a full store update. The check sends the app version, the phone's platform, a random ID made for your install and, like any internet request, your IP address. It never includes your location. See Expo's privacy policy.

Ads in the iPhone and Android apps

• The apps show one banner ad from Google AdMob. To show and measure ads and to prevent fraud, Google's software in the app collects some information from your device, such as its IP address (which gives a rough location, like your city), device and app details, an advertising identifier, and how you interact with ads. The app never gives Google your GPS position. See how Google uses information from apps that use its services and Google's privacy policy.
• iPhone: the app asks Google for non-personalized ads only and never asks to track you.
• Android: ads may be personalized. You can reset or delete your advertising ID in your phone's Settings (Privacy → Ads, or Google → Ads).
• Where the law requires it (for example in the European Economic Area, the UK and Switzerland), the app asks for your choices before showing ads. You can change them any time in the app: open Settings, then Ad privacy choices.
• The web app at depth.hertzmc.com has no ads.

The website

depth.hertzmc.com is delivered by Cloudflare, which counts page visits without cookies (Cloudflare Web Analytics). Measuring happens in your browser.

What the app doesn't do

No accounts or sign-up. No access to your contacts, photos, camera or microphone. We don't collect any personal information ourselves, and we don't sell your information.

Keeping and deleting data

• We keep nothing about you on our own servers, so there's nothing on our side to delete.
• Saved areas and settings stay on your phone until you delete them or uninstall the app.
• OpenFreeMap, NOAA, Google, Expo and Cloudflare keep their data for as long as their own policies say (linked above).
• To ask what data exists or to ask for anything to be deleted, email depth@hertzmc.com. We'll answer and help you with the others if needed.

Children

Ocean Depth Map is not directed at children under 13, and we don't knowingly collect information from them.

Changes

If this policy changes, we'll update this page and the date at the top.

Contact

Questions? Email depth@hertzmc.com.