We have always just taken a phone photo of the passport and keep the original on the ship. We’ve never needed it; however, now that we are older I worry more about an illness or injury that might prevent us from getting back to the ship to retrieve our passports so would consider taking it with us. PS. I have a good travel crossbody bag with an RFID compartment that I always use and keep physically secured when seated. Your age, health, and the availability of an embassy to get a replacement passport in port would be factors to consider.