Ice packs can develop lots of condensation on their surface and the interior of the DemerBox is not waterproof, only the exterior. If you have a type of ice pack that does not develop condensation as it warms up, or if you wrap it in an absorbent material like a Sham Wow, you should be fine. You want to avoid having drops of water drip into the USB, charge port or 3.5mm stereo mini jack.