PADI Distinctive Specialty
Reef Cartographer
Map the reef. Watch it change. A recreational specialty that teaches certified divers to produce georeferenced reef maps — pairing castable sonar for the seabed with photogrammetry for the reef itself — without ever touching living coral.
Why map a reef?
The first thing it changes is you.
A reef can decline for years before anyone notices, because each visitor only ever sees it as it is that day — not as it was. A map fixes a moment. Map the same reef again next season and the two line up: growth, loss, recovery, damage, made specific. Not "reefs are in trouble somewhere," but this reef, these images, this change.
You don't need survey-grade instruments for that to matter — you need an honest record, made the same way twice. But spend three dives mapping a reef and the record isn't the only thing that changes: you won't look at one the same way again.
What you'll make
Two instruments, one honest map
The seabed around a reef — the sand flats, slopes, and channels that frame it — is mapped acoustically with a towed surface sonar. The reef itself is documented optically, frame by frame, with no contact. You then register the two datasets into a single map carrying a stated accuracy.
The result is a documented, repeatable record of a site's structure that can be re-surveyed later to reveal what changed — growth, recession, bleaching, storm damage, recovery. That repeatability is the point of the specialty.
The report
Prepare every survey before you splash
Five client-side calculators turn the geometry of the course into pre-dive numbers — no login, no app, works offline once loaded.
Footprint & Grid Spacing
Sonar footprint from depth and beam angle, and the lane spacing for gap-free coverage.
Refraction & FOV
The true underwater field of view through a flat port, and the corrected frame width.
Baseline & Shutter
How far to move between photos for your overlap, and the camera interval at swim speed.
Orbit Frame Count
Angular step and frame count to circle a target feature with enough overlap.
Accuracy Statement
Your real GPS, scale, datum and checkpoint inputs become an honest limitations statement.
Open all five →
One tabbed app. Each tool feeds the next.
Before the course
Prerequisites & recommendations
Required
- PADI Advanced Open Water (or equivalent) — comfortable with navigation and task loading.
- PADI Enriched Air (Nitrox) — the course dives are conducted on an analyzed mix.
- Solid, demonstrable buoyancy control — this is a no-contact, high-task-load specialty.
Recommended
- PADI Peak Performance Buoyancy — the single biggest predictor of clean data and protected coral.
- PADI AWARE Specialty — the natural conservation companion to reef mapping.
- Counts as one of five specialties toward PADI Master Scuba Diver.
Reef Cartographer is an independent distinctive specialty. The PADI courses above are named as genuine prerequisites and recommendations — Reef Cartographer is not a PADI-owned course.
Interested? Get in touch.
Send me your questions and I'll get back to you with dates, locations, and guidance — wherever you're based.