OceanMAP
Manual Sites FAQ App Store · Available KO EN JA Watch Intro →
PATENT PENDING

OCEAN MAP Underwater navigation.

No extra hardware·No subscription·Underwater nav on your wrist.

A complete real-time underwater navigation system that runs on your Apple Watch Ultra. Dual-band GPS on the surface, sensor fusion (magnetometer · pressure · IMU) underwater — bearing and distance never drop.

Download on the App Store→ Watch the Intro→ 🧭 Try it→ 📘 User Manual→ How it works↓
Now on the App Store · Get it
One-time purchase · No subscription Price $89.99
Apple Watch Ultra iPhone iCloud Sync EN · KO · JA · ZH
Ocean MAP A→B compass navigation screen
DeviceApple Watch Ultra
Depth100m WR · 0.1m
GPSL1 + L5Dual band
SensorsMag · Pressure · IMU
StatusOn the App Store
Intro & How-to Video

How it differs from an analog compass —
and how to use it, in 5 minutes.

🧭 Try it in your browser · 2–3 min→
Why Ocean MAP

No extra gear. No monthly fees.
It already runs on your wrist.

01Hardware

No extra hardware.

No receiver, display or dedicated unit to buy. The Apple Watch Ultra already on your wrist is your nav computer, compass and map.

HARDWAREApple Watch Ultra
02Cost

No subscription.

No monthly or annual fees. One purchase covers every navigation feature and the logbook for life. Sync happens through your own iCloud account.

BILLINGOne-time · Lifetime
03Built-in

Depth & safety
info built in.

Entry and exit are detected automatically — time, track, kick count and water temperature are logged for you. Max depth is entered by hand to complete the record.

SAFETY INFOBuilt-in
ADAPTIVE NAVIGATION

It gets more accurate the more you dive.
It evolves to fit your diving.

Divers don't hold still — you wave, you signal, and every diver's kick is different. Ocean MAP reads that motion and recalibrates to you on every dive.

Diver profile — fins, style and learned stride
01Posture

Steady bearing,
even when you move.

Gyroscope and gravity sensors tell a deliberate compass sighting from hand motion, and gyro and magnetometer cross-check in real time so heading error from a twisted wrist is corrected as you go. Distance advances only on each fin kick, so your position never drifts while you hold still. Sight steady and the bearing is confirmed.

STABILIZESensor-fusion
02Self-calibration

Distance sharpens
dive after dive.

On surfacing, the GPS entry↔exit displacement is compared with the underwater track to learn your fin-kick stride. Distance estimates converge to you over dives — all on-device.

GPS SELF-CALIBRATIONOn-device
03Profile

Starts tuned to
your fins and style.

Fin type and dive style (relaxed · balanced · aggressive) set your initial stride, and kick patterns auto-detect your style — so you start close to your true value from dive one.

DIVER PROFILEPersonalized
Depth & Safety · BUILT-IN

Depth to 6 m,
and we say so below that.

Depth and safety info screen

Logging starts
the moment you descend.

The pressure sensor measures depth in 0.1 m increments and auto-detection picks up dive start and end with no manual input. Apple limits third-party apps to 6 m of depth, so below that we show 6+ rather than a number — a capped reading must never look like a real depth.

Current Depth
6+m
Dive Time
28min
Ascent Rate
0.0m/min
Temperature
14°C

No-decompression limits (NDL) and decompression stops are not provided.
Because depth can only be read to 6 m, calculating and showing decompression figures would be unsafe. If decompression features are ever added, existing owners pay nothing extra.

DIGITAL LOGBOOK · iPhone

After the dive,
everything organizes itself on iPhone.

Dives auto-logged on the Watch sync via iCloud and open up as logbook entries, a site map and statistics on iPhone. CSV export and notes are not paid extras.

iPhone · 01HOME

Home — dive summary

Total dives, max depth and accumulated time as cards. Recent dives sorted chronologically.

iPhone log home screen
iPhone · 02SITES

Site map

Entry points captured automatically; points of interest marked manually. Coordinates and dates stored together.

iPhone dive site map screen
iPhone · 03DETAIL

Dive detail

Max and average depth, dive time, kick count and traveled distance on a single page.

iPhone dive detail screen
PatentPendingUnderwater navigation algorithm application in progress
AlgorithmEKF Sensor FusionMagnetometer · Pressure · IMU fused
AdaptivePersonal stride self-calibrationLearns from GPS ground truth each dive
GPSL1 + L5 dual bandHigh-precision entry-point marking
SynciCloud · Watch ↔ iPhoneThrough your own account
A CHART WE DRAW TOGETHER · OCEANMAP EARTH

A dive site needs
a name.

The app records the coordinates on its own. But only a diver knows what the place is called. After you surface the app asks exactly one thing — the name of this site. Those single lines build the underwater chart at map.oceanmap.co.kr. 3,885 sites are on it today.

01

One line after the dive

Nearby registered sites are offered first. Pick one and it is reused; if there is none, a new site is created.

02

The track is separate

Whether your track goes on the chart is a separate choice, made each dive. Turn it off and the record stays in your logbook only.

03

When paths overlap

As tracks from several divers accumulate, that site's route is promoted to a community path.

04

With the sample count

The chart shows the route together with how many dives back it. One person's track is never shown as an agreed route.

TRAIL CONFIDENCE
Seed — no dives yet
Coordinates only
Collecting 2/3
Tracks coming in
Community · 7 dives
Backed by 7 real dives

You choose every time. Nothing uploads automatically — only when you tap on the screen after surfacing. Contributions are anonymous and carry no personal identifiers. If a site is one you keep to yourself, leave sharing off — the name still stays in your own logbook.

Explore the chart → map.oceanmap.co.kr
DIVE SITES · WORKS WORLDWIDE

Wherever divers go, it comes along.

Strong currents, deep wrecks, atoll mazes — sensor fusion adapts to the navigation challenge each site presents.

PHILIPPINES

Cebu · Moalboal Sardine run · Pescador wall

Sardine-run drift dives and Pescador Island walls. Mark the entry, track drift distance in real time, return to the boat with confidence.

driftwallA→B
PHILIPPINES

Bohol · Balicasag Jack tornadoes

Jackfish tornadoes and steep wall dives. As you follow the wall, it keeps showing the bearing back to your entry point.

wallpelagicbearing
INDONESIA

Bali · Tulamben USS Liberty wreck

The USS Liberty wreck and coral garden. Around the hull, glance at your wrist for the direction to your entry point. Close to a metal hull, magnetic interference can increase heading error.

wreckshallowexit nav
INDONESIA

Nusa Penida Manta Point · Crystal Bay

Manta Point and Crystal Bay drifts. Cumulative travel distance during the drift estimates the recall distance for the boat.

driftmantadistance
JAPAN

Okinawa · Kerama Coral maze

Narrow channels through coral mazes. GPS remembers your entry coordinates, and after ascent the watch points you back to the boat.

coralshallowreturn
THAILAND

Similan Islands White Rock · Elephant Head

Strong-current dive sites at White Rock and Elephant Head Rock. The EKF estimates surface-recovery distance after a drift dive ends.

driftstrong currentEKF
PALAU

Palau · Blue Corner Sharks and mantas

Corner dive with sharks and mantas in heavy current. IMU compensates for posture shifts so the bearing stays stable when the flow grabs you.

sharkcornerIMU comp
MALDIVES

Ari Atoll Channel drifts · Manta points

Channel drifts and manta cleaning stations between atolls. When the boat is out of sight, you can refer to the direction of your GPS-marked entry point.

atolldriftboat return
EGYPT

Red Sea · Safaga Salem Express · Salama

Liveaboard wreck dives at Salem Express and Salama. Record your route around the wreck and refer to the direction of your entry point.

wreckliveaboardtrack log
AUSTRALIA

Great Barrier Reef Cairns

A reef complex large enough to lose your bearings in. Pin your entry by GPS and refer to its direction on your wrist.

reeflarge areasite map
ECUADOR

Galápagos · Darwin / Wolf Whale shark · hammerhead

Pelagic sites for whale sharks and hammerheads. Aggressive current and low visibility demand a fused bearing you can trust through every gust.

pelagicwhale sharkEKF
KOREA

Jeju · Gapado Korean home waters

Home sites for Korean divers. Korean language UI, KST timestamps, and dive site names from OceanMap Earth.

Koreahome base한국어

The sites above are illustrative. Ocean MAP is sensor-based, not location-based — it can be used at most dive sites where magnetic field and pressure can be measured. Error can increase near metal structures or in strong current.

APP STORE · NOW AVAILABLE

Now on
your wrist.

Ocean MAP is now available on the App Store. Dual-band GPS on the surface, magnetometer · pressure · IMU sensor fusion underwater — a true real-time underwater navigation system, together with an automatic dive logbook, all on a single watch.

Price · One-time
$89.99 No subscription
One-time purchase · Lifetime use · No extra hardware
Download on the App Store→
NEXT · INSTAGRAM
Get the news first
Updates, new dive sites and real-world test footage drop on Instagram first.
Follow @oceanmap4

⚠ Ocean MAP is a supplemental dive tool. It does not provide no-decompression limits (NDL) or decompression stops. Depth and ascent-rate readings are for reference only and are not a substitute for a certified dive computer. Always dive with certified equipment. Position, direction and distance are sensor estimates and can be wrong; if you get lost, follow your trained procedures first. Terms of Use

FREQUENTLY ASKED · FAQ

Before launch.

The questions divers ask most often.

Q1Is this a replacement for a certified dive computer?

No. Ocean MAP is a supplemental tool and is not certified to EN 13319 or equivalent standards.

Always wear a certified dive computer alongside Ocean MAP. It does not provide no-decompression limits (NDL) or decompression stops. Depth, ascent rate and temperature readings are for reference only — they cannot serve as the final basis for dive planning or decompression decisions.

Ocean MAP is a navigation (compass · map tracking) tool. For decompression decisions, follow the certified dive computer you wear.

Q2Do I need Apple Watch Ultra specifically? Will a regular Apple Watch work?

Yes — Ocean MAP requires Apple Watch Ultra (1, 2 or 3). It will not run on standard Apple Watch (Series 9 / 10, etc.).

Three hardware requirements drive this:

  • 100m water resistance — only Apple Watch Ultra is certified for diving (EN 13319 case)
  • Dual-band GPS (L1+L5) — needed to mark your entry point more precisely
  • Action button + larger display — essential for marking and confirmation under gloves and low-visibility
Q3GPS doesn't work underwater. How do you track position?

Right before descent, GPS captures your entry coordinates on the surface. Underwater, three sensors estimate position:

  • Magnetometer — real-time bearing (true / magnetic north)
  • Pressure sensor — depth in 0.1m increments
  • IMU (accelerometer + gyroscope) — distance traveled from fin-kick detection

An Extended Kalman Filter (EKF) fuses all three so each sensor's weakness (magnetometer near metal, IMU drift over time, pressure affected by current) is corrected by the others. The return distance and bearing to your entry point are computed by the same model.

Q4How accurate is it?

Depth is measured by the pressure sensor in 0.1 m steps (to 6 m). Direction and distance are estimated from sensors without GPS, so they carry error — current, body position, nearby metal or magnetic interference and device condition can change them significantly.

We will publish accuracy measured in the open sea after our field tests.

Distance error grows with dive time and total travel due to IMU drift accumulation. Each surface re-acquisition of GPS resets accumulated error.

Note: navigation data is advisory only. If you get lost or separated, follow your trained procedures (search, then ascend safely) first, and defer to the dive site's safety procedures and your guide.

Q5How is this different from Garmin Descent or Shearwater?

The biggest difference: navigation is built-in by default.

  • Garmin Descent: $1,000+. Dive-computer-first; navigation is secondary
  • Shearwater Teric: $1,200+. Specialized for Tec / Rec dives, almost no navigation
  • Ocean MAP: $89.99. Installs on the Apple Watch Ultra you already own. Underwater navigation + digital map + logbook in one app

Dedicated dive computers still lead on raw sensor precision and ruggedness. Ocean MAP serves as their navigation supplement — specialized in position tracking and entry-point return.

Q6Do I need to bring my iPhone diving?

No — iPhone is not required during the dive. All core features (compass, map tracking, depth & safety info) run entirely on the Apple Watch Ultra.

iPhone comes into play after the dive: logbook, site map, statistics and notes. iCloud sync is automatic — leave your phone on the boat.

Q7Is there really no subscription? Will pricing change after launch?

Yes — one purchase, lifetime use. No monthly fee, no annual fee, no in-app purchases.

Pricing:

  • Price: $89.99 — one-time purchase, lifetime use. If decompression features are ever added, existing owners pay nothing extra
  • New dive sites and OS-version updates are free

Sync goes only through your own iCloud account. There is no server-side subscription model.

Q8Where can I get it?

It is available now on the App Store — Ocean MAP app page. Install it straight onto the Apple Watch Ultra you already own.

Updates drop first on Instagram @oceanmap4.

Q9What languages does it support?

Ocean MAP supports 7 languages end-to-end: English · Korean · Japanese · Chinese (Simplified) · Spanish · German · French.

The app follows your Apple Watch / iPhone system language automatically, and you can switch in-app mid-dive.

Q10How is my personal information protected?

Ocean MAP has no account sign-up and no server account. Your logs and coordinates stay on your device and your own iCloud by default.

  • Dive logs and GPS coordinates: stored on your device and your own iCloud
  • Contributing to the shared chart (OceanMap Earth) is optional and anonymous — sent only when you tap after surfacing
  • Anonymous usage stats are sent only if you opt in (off by default; change anytime in settings)
  • When transit is needed, it's HTTPS (TLS 1.3) only

See the Privacy Policy for full details.

Didn't find your answer? Reach out at oceanmap44@gmail.com.