I put mine in a passport sleeve
You rarely actually need to bring out a passport, but passports CAN get wet and waterlogged. So I put it in one of these and don't carry the actual passport most of the time: https://www.amazon.com/Seattle-Sports-Waterproof-Passport-Case/dp/B002KT3UMO/ref=sr_1_8?ie=UTF8&qid=1549432744&sr=8-8&keywords=waterproof+passport
I just carry a paper copy of the passport page with me, along with a picture of the visa stamp on my phone.