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Suunto D5 User Guide

Dive modes

By default, Suunto D5 has three dive modes: Air / Nitrox, Free and Gauge (bottom timer). Select the appropriate mode for your dive under Dive settings »Mode. If you select Off, your Suunto D5 can be used as a regular watch. In this case, all dive functionalities are switched off.


Air / nitrox mode

Air mode is for diving with regular air.

Nitrox mode is for diving with oxygen-enriched gas mixtures.

Diving with Nitrox allows you to increase bottom times or reduce the risk of decompression illness. However, when the gas mix is altered or depth increased, the oxygen partial pressure is generally increased. Suunto D5 provides you with information to adjust your dive and stay within safe limits.

In Nitrox mode, both the percentage of oxygen in your tank and the oxygen partial pressure limit must be entered into Suunto D5.

This ensures correct nitrogen and oxygen calculations and the correct maximum operating depth (MOD), which is based on your entered values.

The default oxygen percentage (O2%) setting is 21% (air) and oxygen partial pressure (PO2) setting is 1.6 bar (20 psi).

Air/ Nitrox mode has four views:

  • No deco - The arch shows the no deco time.

    airnitrox nodeco

  • Compass

    airnitrox compass

  • Tank Pressure - For more information on what is shown on the display, see Tank pressure.

    airnitrox tank pressure

  • Timer (visible after customizing with DM5 - The green triangles going up indicate one second.

    airnitrox timer

Multi-gas diving

Suunto D5 allows gas changes during a dive between the gases defined in the Gases menu. When ascending, you are always notified to change gases when a better gas is available.

For example, you may have the following gases when diving to 40 m (131.2 ft):

  • Nitrox 26% (1.4 ppO2) (for bottom)
  • Nitrox 50% (1.6 ppO2) (decompression gas)
  • Nitrox 99% (1.6 ppO2) (decompression gas)

While ascending, you are notified to change gas at 22 m (72 ft) and 6 m (19.7 ft) according to the maximum operating depth (MOD) of the gas.

A pop-up notifies you when to change gases, as shown below:



When Suunto D5 recognizes a better gas is available in the gas list, a pop-up message appears to change gas.


When diving with multiple gases, remember that the ascent time is always calculated with the assumption that you use all the gases found in the Gases menu. Always check that you have only the gases for your current planned dive defined before you dive. Remove the gases that are not available for the dive.


Air/Nitrox dive mode has only one gas in the gas list by default. The Gases menu under this mode will not allow you to add more than one gas. You can activate it by turning multigas diving on in the menu. See also How to customize dive modes with DM5.

To add more gases, activate the multi gas diving by setting Multiple gases 'On' under Dive settings » Mode » Parameters. Your Suunto D5 will restart to save changes. When multiple gases are activated, you can add three gases in total.

You can create additional dive modes using Suunto DM5. See How to customize dive modes with DM5.

Modifying gases during a dive

Modifying gases is for emergency cases only. For example, due to unforeseen events, a diver might lose a gas mixture, in which case the diver could adjust to the situation by deleting that gas mixture from gas list Suunto D5. This allows the diver to continue to dive and get correct decompression information calculated the dive computer.

In another case, if for some reason a diver runs out of gas and needs to use a gas mixture from a dive buddy, it is possible to adapt Suunto D5 to the situation by adding the new gas mixture to the list. Suunto D5 re-calculates decompression and shows the correct information for the diver.


This feature is not enabled by default, it must be activated and creates an additional step to the gas menu during the dive. It is only available if multiple gases are selected for the dive mode.

To enable modifying gases, turn the feature on in the settings menu under Dive settings » Parameters » Modify gases.

When enabled, during a multi-gas dive, you can add a new gas as well as select an existing gas from the gas list to remove it.

Gauge mode

Use Suunto D5 as a bottom timer with Gauge mode.

The timer in the center of the display shows dive time in minutes and seconds and activates at the start of the dive.


Gauge mode is a bottom timer only and thus includes no decompression information or calculations.

Gauge mode has three views:

  • Timer

    Gauge timer D5

  • Compass

    Gauge compass D5

  • Tank Pressure - For more information on what is shown on the display, see Tank pressure.

    Gauge tank pressure D5

  • NOTE:

    After diving in gauge mode, decompression calculation is locked for 48 hours. If during this time you dive again, there is no decompression calculation available and Locked is shown in decompression information fields.

Freedive mode

With Free mode, Suunto D5 can be used as a freediving instrument.

Go to Main menu » Dive settings to activate Free Mode. Suunto D5 will restart to change mode. When you activate Free Mode the display shows you data in white color. Depth is indicated in the unit you set (see How to set language and unit), dive time in minutes and seconds in the center of the display. Temperature information is at the bottom of the display. With the lower button you can change the window at the bottom of the display.

The freedive starts at 1.2 m (4 ft) with water contact or 3.0 m (9.8 ft) without water contact and ends when your depth is less than 0.9 m (3 ft) with water contact or 3.0 m (9.8 ft) without water contact. For more information on the water contact sensor see Water contacts.

Freedive mode has three views by default:

  • Time
  • Depth
  • Compass
  • Timer (only available after customizing)

You can change the views with short pressing the middle button.


Before dives:

Freedive time before dive D5

During dives:

Freedive time during dive D5


Before dives:

Freedive depth before dive D5

During dives:

Freedive depth during dives D5

It is the default view. The white arrow on the left side of the arch moves according to the depth. The yellow arch shows the depth between the max depth (defined by Depth notify 5) and the next deepest active depth notification.


Before dives:

Freedive sompass before dives D5

During dives:

Freedive compass during dives D5


This view is only available after customization.

Before dives:

Freedive timer before dives D5

During dives:

Freedive timer during dives D5

On the surface after freediving

Free mode surface depth view D5

When you are on the surface after freediving, the data on the display turns green. You can view your last depth, the time of your last dive, and the number of dives you have done (white number with a hashtag).

Surface notify

In Timer view the surface interval time is being counted in minutes and seconds at the bottom of the display in a green field until the value you set in Main menu » Dive settings » NOTIFICATIONS » Surface notify.

Free mode surface interval D5

If Surface notify is off, the surface interval counter runs for 4 hours, after that, or after the previously set surface interval time has passed, the counter disappears from the display. Your Suunto D5 will show the following data:

Free mode time view after surface int

Under the surface time icon icon surface D5, the time spent on the surface is shown in hours and minutes in white color.

For setting depth notifications, see How to set depth notifications (freedive only).

Surface timer

While freediving, you can use the surface timer to help you prepare yourself for you next dive. Suunto D5 starts the counter as soon as you reach 0.9 m (2.9 ft).

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