Subsurface or Loggerfish? What each one is good for
Subsurface is a capable, free, open-source logbook. Loggerfish is a newer one with a different emphasis. This is an honest look at what each does, and how to try the other without losing anything.
· 2 min read
What Subsurface lists
Subsurface presents itself as free and open source. It runs on Windows, macOS and Linux, with Subsurface-mobile for iOS and Android. It lists dive computers from about 40 makers that it can download from, by USB, Bluetooth or Bluetooth LE, and its iPhone app downloads from many Bluetooth LE dive computers. It also lists a decompression planner (Bühlmann or VPM-B) on desktop, and an open-circuit planner reached the iPhone app in 2025.
Checked 22 October 2026 · Source: subsurface-divelog.org · Subsurface supported dive computers · Subsurface user manual · App Store: Subsurface-mobile
What Loggerfish does
Loggerfish is a logbook for the web and iPhone, in English, German, Spanish, French and Polish. It works offline, syncs between devices with a free account, and exports every dive as Excel, as UDDF or as a full backup, free on every plan. It imports from SSI spreadsheets, Garmin .fit files, Subsurface logs, UDDF and any spreadsheet. It is not open source; the data is open: you can always take it with you.
Where they differ
- Dive computer download. Subsurface downloads straight from many dive computers. On iPhone, Loggerfish downloads from two, the Mares Sirius and the Shearwater Peregrine TX, over Bluetooth; other dive computers are not supported yet and come in as files. If download from your own computer matters most, check that it is one Loggerfish supports, and otherwise use Subsurface for that.
- Decompression planning. For a full decompression planner, use the planner Subsurface lists above. Loggerfish has planning aids for nitrox, no-stop limits, minimum gas, weighting and gas blending, and says plainly that they are aids and not a dive computer.
- Looking at your own diving. Loggerfish shows air consumption over time, seasons, conditions, trip reports and your year against the last. Those analysis views are part of Pro, the optional paid plan; logging, import, export and sync are free.
- Where it lives. Loggerfish opens in a browser with nothing to install and also runs as an iPhone app. Subsurface is a desktop program with phone companions.
Moving a log in either direction
From Subsurface to Loggerfish: find your Subsurface log file. Loggerfish reads .ssrf files and the .xml that Subsurface saves, with cylinders, profiles and gas changes. Open the import, choose the file and read the preview before you confirm. Your Subsurface file is not touched, so you can keep using both.
From Loggerfish to Subsurface: export UDDF, the open format other logbook programs read. Subsurface's own manual lists what it imports. The Subsurface alternative page has the full list of what to weigh.
Which to pick
If you want to download from a dive computer on your laptop and plan with a full decompression model, Subsurface is built for that. If you want a logbook on your phone that shows what your diving adds up to and never holds your data back, try Loggerfish. Nothing stops you from using both.
Try your Subsurface log in Loggerfish
Free to start, no card. Your logbook, and every export of it, stays yours on every plan.
Names such as PADI, SSI, MySSI, Subsurface, Shearwater and Garmin belong to their owners and are used only to say which product we mean. Loggerfish is not affiliated with any of them. What a guide says about them comes from their own public pages, listed beside the statement with the day it was checked. If something is out of date, write to support@loggerfish.com and we will correct it.