Yes. The Hydroscape App is offline-first. You can open it, browse the HydroLibrary, and submit sightings without any signal. Submissions are saved locally, queued, and uploaded automatically when you're back online.

When you install the app to your home screen, the browser caches the core app files locally. From then on, the app opens and runs without needing a connection.

When you submit a sighting while offline:

  1. The sighting is saved to your device's local storage (IndexedDB)
  2. The form shows a confirmation ("queued for upload") rather than "submitted"
  3. The Hub shows a pending count — how many records are waiting to sync
  4. As soon as signal returns, the queued records upload in the background
  5. Once uploaded successfully, the pending count drops

You don't have to do anything manually. The app handles the queue.

Indefinitely. Your records sit in IndexedDB until they successfully sync. You could log a dozen sightings across a week in the field with no signal, and they'd all sync the moment you got home.

The one risk: if you clear your browser data or uninstall the app before syncing, the queue is wiped. So if you've got unsynced records, let them sync before clearing anything.