These also dry really quickly, so you can just wash them in your hotel room sink, hang them up on the towel rack, and they're likely to be dry by morning. Blisters are caused by your skin rubbing repeatedly against your shoes or socks. With an inner sock layer that sticks on your skin, the outer sock layer does the rubbing against the shoes and keeps your feet happy. There's no such thing as a healthy tan. NO tan is healthy, even that glowing copper skin.
Sunburns are worse.
If you burn so badly that you form blisters, you are in major trouble. Medical personnel treat bad sunburn just like a regular accidental burn, and if your sunburn is bad enough, you might end up in the hospital. If you normally turn pink after 10 minutes in the hot sun, an SPF 20 sunblock will theoretically allow you to stay out for 200 minutes before you must reapply. Chest, including over the parts your shirt seems to cover. Socks can rub some off, so make sure you use plenty.