That's an interesting question. I'll start by saying I don't know. But that won't stop me from responding. :14:
My Cobra manual Technical Specs say just that it's "Salt water calibrated, in fresh water the readings are about 3% smaller. Calibrated complying with prEN 13319)"
It also says it's temperature compensated. Given the overall attention to detail and precision of description implied by the specification, and the lack of anything about altitude adjustment setting in this section, I'd be
very surprised if they assume fresh water for higher altitude settings. Also, there's no description of depth/density impact in the description of the Altitude settings, which say only that they cause the nitrogen-loading models to be modified.
As an engineer, and given that the manual seems to be written by someone who actually cares about precision in specs, I'd bet there is no such auto adjustment. Also, such a linking would IMO violate the user interface "Principle of least Astonishment", see
The cranky user: The Principle of Least Astonishment
There would also be an expected effect on depth accuracy at altitude because the depth sensor assumes something about absolute pressure at zero depth, which is probably increasingly incorrect at higher altitudes, see
Diving At Altitude I see no description in the Suunto manual for that being compensated for, either, but maybe that's covered by prEN 13319.
I tried to find the standard prEN 13319 online, but only found places to buy it. If you want a definitive answer, I think you need to get that, or ask Suunto. If you do, please post what you find out. Thanks for a thought-provoking question.
