Garmin Descent Mk3 / Mk3i setup guide
Also covers: Garmin Descent Mk3, Descent Mk3i
Five-button AMOLED dive watch with touchscreen (LIGHT, UP·MENU, DOWN, START·STOP, BACK·LAP) with Single-Gas, Multi-Gas, CCR, Gauge and apnea modes. Rechargeable; Mk3i adds air integration and dive messaging with a Descent transceiver.
Buttons
| Button | Where | What it does |
|---|---|---|
| LIGHT | left side, top | Turn on; backlight; hold for the controls menu (power off) |
| UP·MENU | left side, middle | Scroll; hold to open the main settings menu |
| DOWN | left side, bottom | Scroll; during a dive, step through the data screens |
| START·STOP | right side, top | Open the activity/dive list; choose a menu option; during a dive, open the dive menu |
| BACK·LAP | right side, bottom | Go back; hold to return to the watch face |
Turn on / wake
Press LIGHT to turn the watch on. On first use, follow the on-screen setup and charge it.
PressLIGHT
Manual p. 8It also has a touchscreen: tap to choose, swipe up or down to scroll, swipe right to go back.
Manual p. 8Use UP and DOWN to scroll, START to choose an option and BACK to go back. Hold BACK to return to the watch face.
PressUP·MENUPressDOWNPressSTART·STOPPressBACK·LAP
Manual p. 8–9Hold MENU (the UP button) to open the settings menu, where Dive Setup and System are found.
HoldUP·MENU
Manual p. 8–9To turn the watch off, hold LIGHT to open the controls menu and select Power Off.
HoldLIGHTPressSTART·STOP
Manual p. 100During a dive, hold functions do not work; press START to open the dive menu and BACK to leave it.
PressSTART·STOPPressBACK·LAP
Manual p. 8–9
Date and time
The manual describes no separate manual date entry; the date comes from the GPS or phone sync.
The watch sets the time and time zone itself when it gets GPS satellites or syncs with the paired phone app.
Manual p. 145To change the format, hold MENU and select System > Time. Choose Time Format (12-hour, 24-hour or military) and Date Format.
HoldUP·MENUPressSTART·STOP
Manual p. 144To set the time by hand, set Set Time to Manual, then use Time to adjust it.
PressSTART·STOP
Manual p. 144After travel or for daylight saving time, use the sync option in System > Time to update the clock.
PressSTART·STOP
Manual p. 145
Units (m/ft, °C/°F)
Hold MENU and select Dive Setup > Advanced Settings > Units to set distance, depth, temperature and tank pressure units for diving.
HoldUP·MENUPressSTART·STOP
Manual p. 12For general watch units, hold MENU and select System > Format > Units, select a measurement type, then the unit.
HoldUP·MENUPressSTART·STOP
Manual p. 146
Water type (salt/fresh)
The manual does not list the water type options; choose the one shown for your dive site. It also affects the gas calculator (p. 33).
Hold MENU and select Dive Setup > Water Type.
HoldUP·MENUPressSTART·STOP
Manual p. 11–12Select the water type that matches your dive site.
PressSTART·STOP
Manual p. 11–12You can also change it on the pre-dive screen: after choosing the dive mode, press UP to edit the dive settings.
PressUP·MENU
Manual p. 25
Dive mode (Air / Nitrox / Gauge)
Auto Dive in Dive Setup can start a dive activity by itself when you descend (p. 12).
From the watch face, press START and select a dive mode: Single-Gas, Multi-Gas, CCR, Gauge, Apnea or Apnea Hunt.
PressSTART·STOP
Manual p. 25For one tank of air or nitrox choose Single-Gas. Gauge is a bottom timer only.
Manual p. 11Press START until the main dive screen appears, then descend. The dive starts at 1.2 m (4 ft).
PressSTART·STOP
Manual p. 25If you dive without choosing, the watch uses the last dive mode and its settings.
Manual p. 25After a Gauge dive, only Gauge or Apnea mode can be used for 24 hours.
Manual p. 11If you stay above a deco ceiling for more than 3 minutes, deco lockout blocks gas dives for 24 hours. Keep Deco Lockout (Dive Setup > Advanced Settings) on.
Manual p. 12
Nitrox O₂% and ppO₂ limit
The manual gives no default PO2 values and does not say that the O2 % resets by itself.
Hold MENU and select Dive Setup > Gases, then select the dive mode (Single-Gas).
HoldUP·MENUPressSTART·STOP
Manual p. 12Select the first gas in the list (the bottom gas).
PressSTART·STOP
Manual p. 12–13Select Oxygen and enter the O2 % of your analysed tank.
PressSTART·STOP
Manual p. 12–13Select Helium and enter the helium %. For nitrox (no helium) this is 0. Press BACK when done.
PressSTART·STOPPressBACK·LAP
Manual p. 12–13Set the MOD limit: Hold MENU, select Dive Setup > PO2 > MOD/Deco PO2, and enter the value your instructor gives you.
HoldUP·MENUPressSTART·STOP
Manual p. 14PO2 Warning and PO2 Critical in the same menu set when the watch warns about high oxygen.
PressSTART·STOP
Manual p. 14
Conservatism / personal setting
The manual does not list the preset level names or values; check the choice on screen with your instructor.
Hold MENU and select Dive Setup > Conservatism, then choose a level.
HoldUP·MENUPressSTART·STOP
Manual p. 11–12Higher conservatism gives shorter bottom times and longer ascents.
Manual p. 11–12The Custom option lets you enter your own gradient factors. Do not use it unless you understand them.
Manual p. 11–12
Altitude
Not available on this computer
There is no altitude setting: the watch adjusts for altitude automatically with its barometric pressure sensor (p. 34).
Audible alarms (depth / time)
Hold MENU and select Dive Setup > Scuba Alerts.
HoldUP·MENUPressSTART·STOP
Manual p. 13Select Add Alert, or select an existing alert to edit it, and turn it on.
PressSTART·STOP
Manual p. 13For a Depth alert set the depth; for a Time alert set the time.
PressSTART·STOP
Manual p. 13Select Sound and Vibe to choose a tone, vibration, or neither. Use Preview Alert to hear and see it.
PressSTART·STOP
Manual p. 14Keep Silent Diving (Dive Setup > Advanced Settings) turned off; when on, it stops all tones and vibration during dives.
Manual p. 12Built-in warnings include Approaching NDL (at 10 and 5 minutes left) and ascending faster than 9.1 m (30 ft) per minute.
Manual p. 34
Reading the log after a dive
From the watch face, press UP or DOWN to the dive log glance.
PressUP·MENUPressDOWN
Manual p. 31Press START to see your most recent dive. To pick another dive, press DOWN, then START.
PressSTART·STOPPressDOWN
Manual p. 31Press START and choose All Stats for the full details, or the depth and temperature graphs.
PressSTART·STOP
Manual p. 31The surface interval glance shows CNS %, OTU, tissue load and no-fly time.
PressUP·MENUPressDOWN
Manual p. 30–31
Battery
To charge, pinch the charging clip, line it up with the contacts on the back and release, then plug in the USB cable. The screen shows the charge level.
Manual p. 148Clean and dry the contacts before charging to prevent corrosion.
Manual p. 148On the pre-dive screen, Battery is low appears below 20% and Battery critically low below 10%. Charge before diving.
Manual p. 34If a battery warning appears during a dive, end the dive and surface safely.
Manual p. 10During a dive, press DOWN on the main screen to see more data, including battery life.
PressDOWN
Manual p. 20
What the main screen shows
The main dive screen shows your breathing gas, PO2 and ascent or descent rate. Single-Gas mode uses Big Numbers by default.
Manual p. 20Press DOWN or double-tap the watch for more data (time, heart rate, battery, max depth) and the dive compass.
PressDOWN
Manual p. 20Ascent rate colours: green below 7.9 m (26 ft) per minute, yellow up to 10.1 m (33 ft), red above that. Tissue load: green, yellow, red at 100%.
Manual p. 21After a dive of at least 11 m (35 ft), ascend to 5 m (15 ft): the safety stop timer counts down when you are within 1 m (5 ft) of the stop depth.
Manual p. 28At the surface the dive ends when the DIVE END timer runs out, or press START and select Stop Dive.
PressSTART·STOP
Manual p. 25
Pre-dive check
Tick each item before you get in the water.