Submersion Dive Log vs Fathom Dive Planner

Submersion is a comprehensive, open-source dive log for recreational and technical divers. Track dives, manage gear, analyze trends, and export to open formats. No subscriptions, no proprietary lock-in, no cost. COMPLETE DIVE LOGGING • Log unlimited dives with depth, duration, temperature, and conditions • Track entry/exit times with automatic surface interval calculation • Rate dives, add notes, and organize with custom tags • Record visibility, current, waves, weather, and water type • Support for 20+ dive types including night, wreck, cave, and technical DIVE COMPUTER INTEGRATION • Connect via Bluetooth or USB to well known dive computer models • Import dive profiles with one tap—no cables to your computer needed • Smart duplicate detection prevents importing the same dive twice • Supported brands: Shearwater, Suunto, Mares, Aqualung, Garmin, Oceanic, and many more ADVANCED PROFILE ANALYSIS • Interactive depth/temperature charts with zoom and pan • Bühlmann ZH-L16C decompression algorithm with gradient factors • Real-time NDL, ceiling, and tissue loading visualization • Ascent rate monitoring with color-coded warnings • O₂ toxicity tracking (CNS%, OTU, ppO₂) for nitrox and trimix divers • SAC/RMV calculation and trend analysis TECHNICAL DIVING READY • Multi-tank support with unlimited cylinders per dive • Full gas mix tracking: Air, Nitrox, Trimix, and pure O₂ • Gas switch markers on dive profiles • MOD, END, and EAD calculations built-in • Tank presets for quick logging (AL80, HP100, Steel 12L, and more) GEAR & EQUIPMENT MANAGEMENT • Track all your gear: regulators, BCDs, computers, suits, and more • Service history with reminders when maintenance is due • Create equipment sets for different diving configurations • Weight calculator based on exposure suit and conditions DIVE SITES & MAPS • Build your personal dive site database with GPS coordinates • Interactive map with clustered markers showing all your sites • Capture location from your phone or pick from the map • Automatic reverse geocoding fills in country and region • Track site details: depth range, difficulty, hazards, and access notes MARINE LIFE TRACKING • Log species sightings with counts on each dive • Pre-loaded database with common species • Build your personal life list over time BUDDIES & CERTIFICATIONS • Manage your dive buddy list with certification levels • Track your own certifications with expiry reminders • Associate buddies and instructors with each dive • Log dive centers and boat names STATISTICS & INSIGHTS • Total dives, bottom time, and depth records • SAC trends over months and years • Temperature preferences by season • Dive frequency charts and gas mix distribution • Deepest, longest, coldest, and warmest dive records CLOUD SYNC & BACKUP • Sync across all your devices via iCloud or Google Drive • Local-first design works completely offline • Export to UDDF, CSV, or PDF • Import from other dive log apps PRIVACY FOCUSED • No account required—start logging immediately • Your data stays on your device (unless you enable cloud sync) • No ads, no tracking, no subscriptions • Open source: inspect the code yourself on GitHub Whether you're a new diver logging your first open water dives or a technical diver tracking complex trimix profiles, Submersion adapts to your needs. Join the growing group of divers who trust Submersion to preserve their dive information. Questions or feedback? Visit our GitHub repository.

Fathom is a native iPhone and iPad app for dive planning and logging. Build open- and closed-circuit decompression schedules with configurable gradient factors, then record every dive you make in the built-in logbook, and link each logged dive back to the plan that produced it. Build single- or multi-level dive plans, manage your gas mixes and tanks, and review every parameter that goes into your decompression schedule before you get in the water. After the dive, capture depth, time, gases, tanks, buddies, locations, and tags in a logbook designed for the same workflow. PLANNING • Configurable gradient factors (default GF 20/85) • Multi-level dive plans with automatic gas selection • Full trimix and heliox support, in addition to air and nitrox • Closed-circuit rebreather plans: fixed setpoints with a switch depth, and travel diluent for deep dives • Open-circuit bailout schedules computed from the worst point of the dive • Repetitive dives: tissue loading, CNS, and OTU carry across surface intervals • Custom gas mixes and standard preset catalogue • Tank and cylinder tracking with SAC and per-tank gas usage • Minimum gas (rock-bottom) reserve required to bring you and your buddy back from depth • NDL (no-decompression limit) at any depth • MOD, END, and gas density for every level, with warnings when a mix gets too dense • CNS clock and OTU oxygen exposure tracking LOGBOOK • Log every dive with depth, time, gases, tanks, location, buddies, and tags • Link each logged dive to its original plan • Browse and search your dive history GENERAL • Metric and imperial units throughout • iCloud sync across your iPhone, iPad, and Mac • One purchase unlocks Fathom on iPhone, iPad, and Mac IMPORTANT Fathom is a planning tool, not a substitute for diver training, qualified instruction, or the judgment of a certified dive professional. Always follow the procedures taught in your training agency, the limits of your certification, and your own dive computer. Decompression diving carries inherent risks. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/