Fathom

Fathom logs recreational dives — depth, gas, time, conditions, the people you went down with. It is offline-first because the moment you need to write a log down is the moment you are on a boat with one bar of signal.

Writes queue locally and reconcile field-by-field when a connection appears, so two devices logging the same buddy dive merge rather than overwrite. Divers log in pairs; last-write-wins loses real data.

We built it alongside a dive club in Split who tested every release on actual dives for a season. The certification-card scanner exists because they asked for it four separate times.