ATMOS MISSION3 Dive Computer Watch
This manual is copyrighted by ATMOS CO. LTD. No part of this document, including images and text, may be reproduced, copied, modified, or stored for personal or commercial use without official written authorization. For updates or additional information on this product, please refer to www.atmos.app.
Safety Instructions
All diving equipment may malfunction or fail. This device can also encounter bugs or issues, so it should not be your sole reference during dives. Ensure you always make thorough diving plans and carry backup devices before each dive.
- Letting the battery completely discharge can greatly reduce its lifespan, and in severe cases, it may fail to turn on. Please fully charge the device every two months when not in use and power it off.
- After diving, soak the device in freshwater and press the buttons several times to flush out any remaining saltwater. Do not use any solvents or cleaners.
- Metals and minerals in the water may react with the device’s body or charging points, causing stains or dirt. If there is moisture on the charging point, wipe it dry before charging.
- The dive computer is a precision instrument. Avoid impacts, heavy pressure, direct sunlight, or storing it in vehicles exposed to the sun. Do not use it in steam rooms, hot springs, or any environments other than recreational diving.
- Avoid relying solely on the automatic dive mode. It is recommended to switch to dive mode manually before each dive.
- Follow the decompression stop instructions displayed on the device.
Ignoring them greatly increases the risk of decompression sickness, which may lead to injury or death. - This device is not designed for commercial diving use. Do not use it for commercial diving.
- This manual corresponds to firmware version VXXX. Future updates may not be immediately reflected in the manual. For the latest firmware updates, visit Atmos.app/support.
Package Contents
- MISSION3 unit and silicone strap
- USB Type-C charging cable
- Quick start guide and warranty card
- Two screen protectors
- Two strap bars
Getting Started
Button Functions
- E Button
Short press: Backlight
Long press: Button lock - D Button
Short press: Exit - A Button
Short press: Scroll up
Long press: Bluetooth on/off - B Button
Short press: Confirm
Long press: Timer - C Button
Short press: Scroll down
Long press: Stopwatch
The long-press shortcuts can be changed in Settings > Shortcuts.
Power On/Off
- Power on: Long press the E button, or connect the device to the charging cable.
- Power off: Press the D button to enter the function menu => Power off.
Forced restart: Press and hold the A, B, and C buttons simultaneously for 6 seconds.
Charging
Please use a certified charger with a rated voltage of DC 5V/3A. Make sure the charging points are dry and the charging clip is securely attached before charging.
The battery life of the device depends on settings such as screen brightness, screen active time, Bluetooth, vibration, sound, GPS, gesture backlight, etc.
Turning off unnecessary features can extend the battery life.
If the battery remains discharged for a long period, it will significantly reduce its lifespan, and in severe cases, the device may not power on. Please fully charge the device every two months when not in use and power it off.
Connecting to Your Mobile Phone
Pairing with Your Phone
- Download the ATMOS App.
- Turn on Bluetooth on your phone.
- Enable the dive computer’s connection feature (from the function menu > Connection).
- Register and log into the ATMOS App, then tap the watch icon in the upper left corner. Select “+” or “Pair a new device.”
- Find your dive computer on the device list (M3-XXXX) > Pair > Enter the pairing code shown on the watch display > Complete the pairing.
Unpairing/Re-pairing
If you change phones or encounter connection issues, follow these steps to unpair:
- On the dive computer, go to the function menu > Connection > Select Unpair.
- On your phone, go to the Bluetooth device list > Forget your device.
- In the ATMOS App, go to the device list > Remove the device.
- Tap the watch icon in the upper left corner. Select “+” or “Pair a new device.”
- Find your dive computer on the device list (M3-XXXX) > Pair > Enter the pairing code displayed on the watch > Complete the pairing.
Scuba Diving Mode
Air / Nitrox/ Multi-gas Diving
Main Screen (NDL)
- Top: GPS marker (green indicates a successful GPS lock)
- Upper left: Compass heading (if “∞” is displayed, calibration is required)
- Upper right: No-decompression limit (NDL) time (if it exceeds 99 minutes, “99+” is displayed)
- Left: Water temperature | Ascent/descent rate bar (shown during diving)
- Center: Dive depth
- Lower center: Dive time
- Bottom: Active gas mixture | Battery level
Compass Screen
Press C Button to cycle through different screens.
Before diving, press B Button to adjust dive settings.
Press A Button to lock the heading. The locked direction will be displayed with a green arrow, while the opposite direction is indicated by a white arrow.
Press A Button again to cancel the locked heading.
Stopwatch & Custom Screen
Press C Button to cycle through the screens.
Before diving, press B Button to adjust the dive settings.
Dive Stopwatch
Press A Button to start the stopwatch, press again to stop it (note: there is no pause function).
Custom Dive Info Page
Before diving, press B Button to enter the dive settings. On the custom page, you can set which information is displayed in each field. Options include: current depth, water temperature, surface time, dive time, ascent/descent rate, NDL, CNS%, average depth, maximum depth, time to surface (TTS), compass heading, and battery level.
Time to Surface (TTS)
TTS is displayed in minutes and represents the time required to ascend at a normal rate, including any required decompression and safety stops. The default ascent rate is 10 meters per minute (33 feet per minute).
Gauge Diving
Non-Decompression Calculation
Gauge diving mode only displays depth and bottom timer (BT) functions. There is no decompression calculation, so no information about safety stops or decompression stops is provided.
Gauge Mode Lockout
After a gauge mode dive, for safety reasons, the air/nitrox/multi-gas dive modes will be locked for 24 hours. During this time, only gauge mode can be used. You can unlock this from the menu: Advanced Settings.
Scuba Diving Events & Alarms
The alarms for different dive modes vary. Here are the main events and alarms for scuba diving:
Starting/Ending a Dive
Starting Depth:
When descending to a depth of 1.2 meters, the dive will automatically start.
The dive will end when ascending above 1.2 meters.
You can adjust the delay time for ending the dive.
Depth Alarms
Depth Reached:
When you reach the set depth, a notification or alarm will be triggered.
You can set up to 10 depth reminders and 1 alarm (which repeats).
Time Alarms
Dive Time Reached:
When you reach the set dive time, a notification or alarm will be triggered.
You can set up to 10 time reminders and 1 alarm (which repeats).
Ascent Rate Alarm
Ascent Rate Too Fast:
If the ascent rate exceeds 12 meters per minute for five consecutive seconds, the MISSION3 will trigger a “Fast Ascent Alarm.”
Safety Stop
Starting Safety Stop:
After diving deeper than 10 meters, the safety stop will start when you ascend to 6 meters.
Pausing Safety Stop:
The valid safety stop depth range is 3–7 meters. If you go outside this range, the countdown will pause.
If you descend deeper than 10 meters, the safety stop will reset.
Completing Safety Stop:
Once the countdown finishes, a notification will be triggered.
Decompression Stop
Approaching Decompression:
When the NDL (No-Decompression Limit) drops below 3 minutes, a reminder will be triggered every minute.
Decompression Stop (DECO):
When the NDL is exhausted, the dive enters decompression (DECO) mode. You must ascend and perform a decompression stop at the indicated depth to reduce the risk of decompression sickness (DCS).
The display will show, for example, a stop at 6 meters for 5 minutes.
Since ascending is part of the decompression process, the stop may complete during ascent, returning you to the NDL dive screen.
Decompression Violation:
If you ascend shallower than the decompression stop depth, the device will issue a
“Decompression Required” alarm. If gas supply allows, descend to below the required decompression stop depth to complete the stop and reduce the risk of DCS.
Remaining Air Pressure Check
Set a dive time, and when reached, the device will remind you to check the
remaining air pressure.
You can set up to 10 reminders.
CNS (Central Nervous System) Oxygen Toxicity Warning
When CNS% reaches a specific threshold, the device will issue a reminder.
MOD (Maximum Operating Depth) Alarm
When you reach the MOD, the device will continuously issue an alarm. You must ascend immediately.
Surface Interval Reminder
Set a specific surface interval (S.I.) time to remind you when to prepare for the next dive after finishing a dive.
Low Battery Warning
When the battery level is low, an alarm will be triggered.
Air/Nitrox Settings (Single Tank Recreational Diving)
On the dive screen, press B Button to enter the menu. You can choose between air and nitrox. Nitrox can be set from 22% to 40% oxygen.
Multi-Gas
In multi-gas diving, press B Button on the dive screen to enter the menu. You can set the gas composition for two tanks, and nitrox can be set from 22% to 50% oxygen.
During the dive, press B Button to switch between gases.
Conservatism
Adjusting the conservatism setting can give you more or less no-decompression time. It is recommended not to change this unless you fully understand its effects.
Options: Normal, Conservative, Lenient, Custom (with adjustable GF values).
GF (Gradient Factor)
Gradient Factor (GF) values affect decompression calculations. Adjusting GF without a proper understanding may result in incorrect decompression information.
Reference link: About GF Values.
It is recommended to consult resources or experts before changing GF values.
Surface Interval
Set the surface interval (the time between dives) and the target depth. The device will calculate the no-decompression limit (NDL) for your next dive.
Cylinder Volume
Before diving, input the cylinder volume and starting pressure. After the dive, input the ending pressure when saving the dive log, allowing you to review your Surface Air Consumption (SAC) rate.
The typical aluminum cylinder in Asia is 11.1 liters. Reference: Cylinder Volume Information.
Scuba Diving Logs
Dive Event Markers
- Red Dot: Fast ascent
- Yellow Dot: Time or depth alarms
- Green Dot: Safety stop
- Press A Button or C Button to scroll through the pages.
- Press B Button to delete the log.
Freediving
Freediving Events & Alarms
Starting/Ending a Dive
Starting Depth:
The dive starts automatically when descending to 1.2 meters and ends when ascending above 1.2 meters.
You can adjust the delay time for ending the dive.
Freediving Depth Alarms
Descending Depth Reached:
When you reach the set depth, a reminder or alarm will be triggered.
Up to 10 depth reminders can be set.
Freediving Ascent Alarms
Ascending Depth Reached:
When you ascend to the set depth, a reminder or alarm will be triggered.
Up to 10 ascent reminders can be set.
Freefall Depth Alarm
A preset freefall depth alarm will trigger when you reach the set depth during descent.
KEEP DEPTH Alarm
A preset depth will trigger an alarm when the set depth is reached during the dive.
Time Alarms
When the set dive time is reached, a reminder or alarm will be triggered.
Up to 10 time reminders can be set.
Surface Interval Reminder
You can choose between preset, custom, or off options. Presets:
- Surface interval time is twice the dive time.
- If the depth is greater than 30 meters, the reminder time is calculated as the depth divided by 5 (in minutes).
Hydration Reminder
Set a specific time to receive reminders to hydrate during surface intervals.
Low Battery Warning
When the battery level is low, an alarm will be triggered.
Freediving Logs
Press A Button or C Button to scroll through the log pages.
Press B Button to delete the log.
GPS
GPS Usage Notes
GPS should be used in an open environment without obstructions, as interference can affect positioning speed and accuracy.
GPS is only usable on the water’s surface. When using GPS, keep the watch face towards the sky.
Use the “Sync GPS” function in the ATMOS App to reduce positioning time.
Depending on satellite conditions and interference, successful GPS acquisition cannot be guaranteed 100% of the time.
Dive Spot Function
Marking Entry/Exit Points
Entry Point GPS:
When switching to dive mode, GPS will activate. If the GPS icon turns green, this indicates a successful GPS lock, and your entry point will be recorded.
Exit Point GPS:
Upon returning to the surface, GPS will be reactivated. Keeping the watch at the surface will increase the likelihood of recording your exit point’s GPS coordinates.
Nearby Dive Spots
Displays the 10 closest dive spots, including both those from the ATMOS database and user-created spots.
After selecting a dive spot, the direction and distance to the spot will be displayed.
To maintain guidance, keep the watch at the water’s surface.
User-Created Dive Spots
After acquiring GPS coordinates, you can save your current location.
You can view or edit the names of user-created spots via the ATMOS App under Your Device > Device Dive Spots.
Settings Menu
Default Dive Mode (Automatic Dive Start)
Do not rely solely on the automatic dive mode. It is recommended to manually switch to dive mode before each dive.
The automatic dive start checks water pressure every 10 seconds, which means that dive mode may not activate until 10 seconds after submersion.
Watch Face Settings
Customize your watch face with widgets, including tide information, flight ban time, surface interval (S.I.), and more.
Flight Ban / Surface Rest Time
After a dive, residual nitrogen remains in the body. To avoid decompression sickness caused by pressure differences, wait until the flight ban time ends before flying or ascending to an altitude above 300 meters (1,000 feet).
Flight Ban:
After scuba diving, a 24-hour countdown is initiated.
After freediving to a depth of 40 meters, a 12-hour countdown is initiated.
Surface Rest / Surface Interval (S.I.)
After finishing a dive, the S.I. timer counts down from 24 hours.
Last Dive Review
Displays the details of the most recent dive, including event markers and any warnings.
Smart Notifications
Incoming calls and messages will trigger notifications on the watch.
To enable smart notifications, go to Menu > Settings > Connection > Smart Connect.
On the watch screen, press A Button to view the notification details.
Restarting the watch will clear the notifications.
If you select “Calls Only,” only incoming call and SMS notifications will be shown, excluding app notifications.
Compass
Due to the presence of magnetic interference in daily environments, it is recommended to calibrate the compass before each dive.
When wearing the device, avoid placing it near other dive computers, magnetic objects, or metallic items.
Compass Calibration
When the compass heading shows an incorrect reading or “∞” symbol, calibration is required. To calibrate, perform a figure-8 motion with the watch. Once completed, the correct heading will display.
Calories
The watch tracks your estimated calorie burn based on your activity levels and data.
Sleep Tracking
MISSION3 provides sleep tracking features to monitor the quality and duration of your sleep.
Tide Information
MISSION3 includes tide information, which you can customize based on your location.
Step Counter
MISSION3 has a step counting feature that tracks your daily steps.
Power-Saving Settings
The device’s battery life depends on settings such as screen brightness, active time, Bluetooth, vibration, sound, GPS, gesture backlight, etc. Disabling unnecessary features can significantly extend battery life.
When the power-saving mode is enabled, if the watch remains idle for two days, it will automatically power off.
Firmware Upgrade
Regular firmware updates can resolve bugs, improve stability, and add new features.
View Firmware Version: Go to Menu > System > About to check the MAC address, serial number (SN), and firmware version (FW).
How to Update Firmware
Using a Computer (Recommended)
- Switch to firmware update mode: On the watch screen, press D Button to enter the menu > System > Update.
- Connect the MISSION3 to your computer using the charging cable: The device will appear in your computer’s device list as “MISSION3.” Open the FIRMWARE folder.
- Download the latest MISSION3 firmware update file from the ATMOS website (https://www.atmos.app/zh/support/#firmwareupdate), unzip it, and copy the M3_xxxx.bin file into the FIRMWARE folder. Once the file transfer is complete,disconnect the charging cable, and the MISSION3 will automatically begin updating.
Using the ATMOS App
- Pair and connect your MISSION3 with the ATMOS App > Your Device.
- If the firmware is not up to date, a “New Version!” notification will appear next to the Firmware Update option.
- Click “Update” and confirm, keeping MISSION3 synced with the App. Do not disconnect the network during the process.
- Once the file transfer is complete, MISSION3 will automatically start the update.
Transfer time varies depending on the device: iOS takes approximately 5-10 minutes, while Android takes about 30-40 minutes.
Resetting the Device
Clear All Logs: Clears all saved dive and freediving logs.
Factory Reset: Restores the device to its original factory settings.
Quick Factory Reset Shortcut: Available for easy resetting in the settings menu.
Straps / Drysuits
Changing the Strap
To change the strap, push the strap spring bar to the right and lift the strap to remove it. If you need to switch to another type of strap, use the quick-release strap bars included.
Straps are consumable items and should be regularly inspected and replaced. For new straps, contact your dealer or ATMOS.
Drysuit Straps
If you are using a drysuit, you can purchase a longer strap (22.3 cm) from your dealer or ATMOS.
Proper Care
Letting the battery discharge completely can greatly reduce its lifespan, and in severe cases, it may fail to power on. Fully charge the device every two months when not in use, and power it off.
After diving, soak the device in freshwater and press the buttons several times to clean out any salt or debris. Do not use any solvents or cleaning agents.
Water contains metals and minerals that may react with the watch body and charging points, leading to stains or dirt. If the charging point is wet, dry it before charging.
The dive computer is a precision instrument. Avoid impacts, heavy pressure, or exposure to direct sunlight. Do not use it in environments like steam rooms, hot springs, or places other than recreational diving.
Store the dive computer in a cool, dry, and dust-free environment, away from direct sunlight. Avoid exposing it to ultraviolet radiation or radiant heat.
AMOLED Screen Characteristics
Screen burn-in on AMOLED displays is a normal aging phenomenon. Avoid displaying static images and data at high brightness for long periods. The screen will automatically turn off to extend its lifespan.
Repair Information
This device does not contain user-serviceable parts. Repairs and battery
replacements can only be performed by ATMOS or an authorized service center.
Do not attempt to tighten or remove screws. Any modifications will void the warranty.
For after-sales support or repair inquiries, contact the dealer/distributor from whom you purchased the device or reach out to ATMOS Taiwan at info@atmos.app. Other
Screen Protectors & Anti-Loss Measures
MISSION3 comes with two high-transparency glass screen protectors. Since the dive computer is a precision electronic device, avoid direct impacts with hard objects. When entering or exiting the water, turn the screen inward toward your wrist, and protect the device during transport.
If the screen protector is damaged, contact your dealer or ATMOS to purchase a replacement.
Straps and screws are consumable parts, and regular inspections are advised.
Replace any worn parts as needed.
Tip: Use a lanyard to attach to the MISSION3 as a safety measure to avoid losing it. High Altitude
MISSION3 automatically detects environmental pressure. When at high altitude, the depth values will be automatically adjusted. Just switch between fresh water and saltwater settings.
FCC Warning Statements
FCC 15.19
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:
- This device may not cause harmful interference.
- This device must accept any interference received, including interference that may cause undesired operation.
FCC 15.105 (for FCC 15B devices)
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation.
This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation.
If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
- Reorient or relocate the receiving antenna.
- Increase the separation between the equipment and receiver.
- Connect the equipment to an outlet on a different circuit than the receiver is connected to.
- Consult the dealer or an experienced radio/TV technician for help.
FCC 15.21 (User Information)
Any changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment.
This equipment complies with FCC RF radiation exposure limits set forth for an uncontrolled environment for body-worn configuration in direct contact to the phantom.
Documents / Resources
 | ATMOS MISSION3 Dive Computer Watch [pdf] User Manual MISSION3, MISSION3 Dive Computer Watch, Dive Computer Watch, Computer Watch, Watch |
