UDDF explained: the open file format for moving a dive log

What UDDF is

UDDF stands for Universal Dive Data Format. It is a plain text file, written in XML, that logbook programs read and write, usually with the ending .uddf. It can hold dive sites, dates and times, depth, length, the gases and the depth profile. Depth, time, temperature and pressure are written in SI units: metres, seconds, kelvin and pascal. Because it is open, a UDDF file keeps working when the program that made it does not.

Where it comes from

Most dive computers do not write UDDF themselves. It is what a logbook program exports after it has read the computer.

Shearwater says Shearwater Cloud can export dives as UDDF (or XML). Its help pages do not spell out the menu steps, so the steps in our Shearwater guide follow the desktop app's File menu as divers describe it, and names may differ in your version.

Checked 25 October 2026 · Source: Shearwater: Shearwater Cloud

What Loggerfish reads

Loggerfish reads a UDDF file as it is, with no columns to match. Wherever the file has them, it takes:

• Date and time, site name and country, maximum depth, dive length, water temperature, visibility, buddies and notes.
• Cylinders with their size, pressures and gas mix, the gas changes during the dive, and the air consumption worked out from them.
• The depth profile with temperature, tank pressure, no-stop time, oxygen partial pressure, ceilings, heart rate and CNS, and the dive's alarms.
• Where the dive started from, such as shore or boat, and the altitude. If the file numbers its dives, the preview asks whether to keep those numbers or continue from your own last dive.

What it leaves out

Loggerfish does not read a site's coordinates from UDDF, so a dive comes in with the site's name but not its place on the map. Ratings, photos, gear, weights, suit, certification, tags, dive type, current and surface conditions, air temperature, instructor and dive operator are not read, even if the file holds them. A dive with no date, or with no site, no depth and no length, is not imported; the preview lists it with the reason.

Moving a logbook in two steps

1. Export UDDF from the program that holds your dives.
2. Open the import in Loggerfish, choose the .uddf file and read the preview. It counts the dives that are new, the ones already in your log and the ones that differ. Nothing is saved until you press import, and importing needs no account because the file is read on your own device.

There are step-by-step pages for Shearwater Cloud, MacDive and Subsurface.

After the import

Compare the dive count and your deepest dive with the old program. Then keep a copy of your own: Loggerfish exports Excel, UDDF and a full backup, free on every plan, so the logbook can move again.