Pelagia vs Submersion Dive Log

Pelagia is an offline-first dive log built by scuba divers for scuba divers—made to feel like the logbook you always wanted on the boat, and the journal you’ll want to read years later. Offline-first means you don’t need an Internet connection, so it works wherever you do. It’s a great fit whether you want clean, reliable records pulled straight from your dive computer, or you want to capture the whole story of a dive: conditions, team, gear, how it felt, and the photos or video that bring it back.

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.