To set a sonar mark in the Fish Deeper application, follow these steps:
During your fishing session, look at the sonar scan on the right side of the screen.
Tap and hold on the part of the sonar scan you find interesting (e.g. fish arches, bottom structure).
After holding for a moment, a mark will automatically appear on the left-side map. Your phone will also vibrate to confirm that the spot has been marked successfully.
This mark shows the exact GPS location where that sonar reading was recorded.
The marked spot is saved and can be edited later with details like notes, photos, time & date, and more.
This feature works during live scan, during rewind of the scan, and when viewing scans in Scan History.
Here’s a video showcasing this process: