Don't be fooled into thinking that "too much sun is never enough." This sun at this latitude means it will always been sunny and warm, but in the summer the sun is extremely intense. People who are not acclimatized to such intense heat and humidity can experience dehydration and faintness in a short period of time.
Always use sunblock, the higher the SPF number the better. Wear a wide brimmed hat (ladies) or cap (men), sunglasses and light clothing. Drink water, drink water and drink more water!! Bring a handheld mister fan at the very least and stop and rest in the shade the minute you feel any dizziness or faintness.
You might think "margaritaville" is a sun worshiper's paradise, but don't be foolish and risk getting an intense sunburn or worse. If you're beet red, getting chills when the temperature is 95F, have a headache and sick as a dog, you probably have serious skin burn; if you've fainted, you probably might have heatstroke.
Try to see as many sights in the early morning or early evening as you can, and rest in the middle of the day.
Look closely at the man in the accompanying picture----he's had TOO MUCH SUN!!!
Well, at least you can't say it "snuck up on you". It doesn't take a Rhodes Scholar to know that it's hot and sunny in Key West. So, for dermatology's sake, please take care of yourselves in the intense Caribbean sunshine.
Buy a nice hat and find some sunscreen, too. Make copious use of beach or pool umbrellas, and take opportunities to move indoors during the hottest periods of the day.
You don't want your skin to look like that abandoned suitcase you saw circling the baggage claim carosel when you get older, do you?
The sun can be pretty intense in So Florida, being closer to the equator and all. Even if it is cloudy you can still get burned.
Wear the sunscreen and save yourself the pain.
If you do get burned - even just a litttle - Banana Boat makes a great after sun lotion. It has vitamin E and aloe vera.