Any way to disable saving in a certain area?

I have some underwater type areas with a timer that if saved the timer will reset on load so saving there can abuse the system, or it might be a bad place to save in general. So i am trying to figure a way to disable saving in those areas only. Thanks

Make a collision box or something, when player enters, set saving possible (another variable you have to make somewhere) to false. When they leave, set it to true