Possible Safety-Critical Suunto Nautic Bug – Tissue Desaturation May Stop While Device Is Powered Off
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I would like to report a possible safety-related decompression calculation issue with my Suunto Nautic.
I experienced an unexpected decompression obligation during a recreational air dive on September 26, 2026. After reviewing the FIT and JSON dive logs in detail, I am seeing that the Nautic is not correctly applying tissue off-gassing/desaturation for time during which the device is completely powered off.
My hypothesis is that the Nautic correctly stores the tissue compartment state when it is powered off, but may not correctly advance/desaturate those compartments for the real elapsed surface time while the device remains powered off. The decompression model should produce the same tissue state after a given real surface interval regardless of whether the Nautic remained powered on or was completely powered off.
The issue may be that tissue desaturation is being updated by an internal runtime process while the device is powered on, but that the same elapsed time is not retrospectively applied to the tissue compartments when the Nautic boots after being powered off.
Please escalate this report to the team responsible for the Nautic decompression algorithm and persistent tissue-state handling.
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@marcin.brys it is better if you also contact support directly
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@isazi just emailed ‘support-en@suunto.com’ with details.
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