Make sure you're using a SanDisk SD card with min. U3 speed rating - other SD cards are not supported and might cause freezing and/or not saving footage.
- If you film from the moment you enter the water until the camera runs out of battery or until your dive is done, the 128GB SD card is the best option
- If you like to use the camera on multiple dives or multiple charges without having to empty the SD card in between, then the 128GB SD card is also the better option
- If your film for less than an hour every time you bring the camera and you usually empty the SD before you need the camera again, then you can use the 64GB SD card