Import a Subsurface logbook: step by step, and what comes across

Before you start

You do not have to leave Subsurface to try this. The import only reads your file and never changes it, so you can carry on using both. If you already compare the two, our Subsurface or Loggerfish guide covers what each is good at. This one is only about moving the dives. It costs nothing to put a copy of your log file somewhere safe first, though the import does not need it.

Step 1: save your log in Subsurface

Subsurface's manual says that edits are kept in memory and are not written to storage until you save, and that on closing it asks whether the dive log should be saved. So save first, or the file you import will be missing your latest dives.

Checked 23 October 2026 · Source: Subsurface user manual

Step 2: find the file

Find the log file you open Subsurface with. Loggerfish reads the .ssrf file, and also the .xml that Subsurface saves. You do not need to export UDDF or a spreadsheet first, and you do not need to match columns. If you keep several log files, bring in the one with the dives you want, and repeat for the others; dives that are already in your Loggerfish log are recognised and not added twice.

Step 3: open the import

In Loggerfish, open the import (on an empty logbook it is offered on the first screen) and choose the file. Importing needs no account, because the file is read on your own device. Nothing is saved yet.

Step 4: read the preview

The preview counts what would happen: how many dives are new, how many already match one in your log, and how many match but differ. Look at the differences before you accept. Nothing is overwritten without you seeing it, and an import can be undone afterwards.

If the dives carry the numbers Subsurface gave them, the preview asks whose numbering to keep: the file's, or a continuation from your own last dive. If your logbook already uses some of those numbers, it warns you before you choose.

What comes across

For each dive, the import reads the date and time, the site and its position if Subsurface has one, maximum and average depth, and the dive time. It also reads:

• Gas. Every cylinder, with its size, pressures and mix, including the gas changes during the dive. Subsurface writes units into its values, so a log kept in feet and psi is converted to metric rather than read as metres.
• Profile. The depth samples, when the file has them.
• People. Buddy, and the divemaster as their own field, not as an extra buddy.
• Extras. Notes, rating, tags, the dive computer's name, water temperature, and trips: dives grouped in a Subsurface trip appear as a trip.

A dry suit in the suit field marks the dive as a dry-suit dive.

What is left out

Loggerfish says what it did not keep, under "What was left out" in the preview. Two examples: Subsurface rates visibility from 0 to 5, while Loggerfish stores visibility in metres, and a rating is not a distance, so it is not guessed; and air temperature has no field here. Some profile events that the logbook does not draw are left out too, and listed by name. Dives with no date, or with neither a site nor a depth nor a time, are skipped and reported with the reason.

After the import

1. Compare the dive count and your deepest and longest dives with Subsurface.
2. Open a dive with several cylinders and check the gases.
3. Export a copy of your Loggerfish log. Export as Excel, UDDF or a full backup is free on every plan.

Loggerfish does not download from a dive computer today: it reads files. Keep Subsurface for downloading if that is how you work, and import the results.