Hi @Tides,
Low external temperatures can definitely help avoid your electronics overheating, but that’s reliant on heat transfer, which depends on the materials you’re using and the interfaces between them.
As an example, if you’ve got an unmodified GoPro in a fully acrylic enclosure then it would be challenging for heat to get out. In comparison, @nperry has previously modified a GoPro to include a heat sink, along with some other nice features for operating underwater.