Free dive logbook — log every dive

Your dive log is the record of every dive you make — and the data your next dive plan is built on. DecoLog is a free digital dive logbook that runs in your browser and works offline: log depth, time, gas, decompression and equipment, and watch your trends build over time. No signup, no subscription, no ads.

A digital dive log that goes everywhere

Paper logbooks get wet, get lost, and get left at home. A digital dive log keeps the same record — date, site, buddy, depth, bottom time, conditions and rating — searchable and backed up across every device. DecoLog is offline-first, so your logbook lives on your device and is ready dockside or on the boat with no signal; sign in and it syncs across phone, tablet and desktop.

What to record in your dive log

• The basics — date, site, max depth, bottom time, water and air temperature, visibility, buddy and a rating.
• Gas — cylinder size, mix (air, nitrox or trimix), and start/end pressure, so DecoLog can work out your consumption automatically.
• Profile — your depth/time profile, safety stop and any decompression stops.
• Equipment — exposure suit, weighting and what worked, so the next dive starts from a known setup.

Why technical divers log every dive

For a technical diver the logbook isn't nostalgia — it's data. Your gas consumption at depth is the single number every dive plan depends on, and the only way to know it is to log real dives and let the trend emerge. Beyond that, tech and rebreather divers record the exact mix and decompression gases breathed, the algorithm and gradient factors or VPM-B conservatism used, CCR setpoints and diluent, scrubber duration burned, and hours on regulators, oxygen cells and other life-support gear for service intervals. DecoLog tracks all of it.

SAC / RMV trends that make you a better diver

Because DecoLog knows your cylinder size and start and end pressures, it turns every logged dive into a surface-air-consumption (SAC) and respiratory-minute-volume (RMV) figure and charts the trend. Watch your gas planning tighten as your buoyancy and comfort improve — then plan future dives off your real numbers instead of a guess.

Free, offline, and yours

DecoLog's dive log is free forever — no subscription, no paywall, no ads. It keeps working with no signal, syncs when you sign in, and exports to PDF when you need a printable record for a course sign-off or your own files.

⚠ DecoLog records and analyses your dives — it is a logbook and planning aid, not a substitute for proper training or a dive computer. Always dive within your certification and verify critical data independently.