The Phoozy Thermal Capsule XP3 does well to protect smartphones from extreme heat and cold and is a valuable addition to your wilderness pack
These are just a few things to consider when planning and packing for a kayaking trip. The biggest thing about kayaking is to remember to enjoy it. Put your phone in a dry box or in the dry storage so it doesn't take a swim without you. You can also use something like a PHOOZY to protect it.