Subsurface can plan and track single- and multi-tank dives using air, Nitrox or TriMix. It allows tracking of dive locations including GPS coordinates (which can also conveniently be entered using a map interface), logging of equipment used and names of other divers, and lets users rate dives and provide additional notes.
You can tag dives and filter a dive list based on criteria including tags, locations and people with whom you were diving. You can group the dive list into trips, and edit multiple dives at the same time, making it easy to support a large number of dives.
Multiple divers can share one instance of Subsurface using different preferences and settings.
The program is localized in about 20 languages and well supported by an active developer community.
One of the major strengths of Subsurface is its support of a wide range of dive computers (see the list of supported dive computers). Subsurface can also import existing dive logs from several sources including MacDive, Suunto DM3, DM4 & DM5, JDiveLog and divelogs.de.
Another strength is its ability to visualize the depth profile (and, if available, the tank pressure curve) in innovative ways that give the user additional information on relative velocity, and momentary air consumption, during a dive. Users who dive with multiple dive computers can combine the data from each of their dive computers into one dive – allowing visualization of the data collected from multiple sources.