But the issue is how that works mechanically. This is a computer game so there has to be a relatively simple means of determining when to set permafrost on (from what it looks like you're saying) This is a persistent world, not instances so it'd be pretty difficult for player intent to modulate the game rules. As it stands the rules are simple and consistent: Deep sea travel is extremely perilous. And the reasons that permadeath occurs is consistent with the current rules. What you are arguing for is an exception and a partial one at that, which is a bit extreme before we get any indication of how that plays out in game.
Voicing your concerns is important though, so this thread definitely serves a purpose, but I have to disagree with the statement that the current proposed system is unfair or problematic