I remember having Acne when I was younger and going to the Domican for a week of the salt water, humidity and sun had my skin looking great. Actually I don't think I broke out for 6 months afterwards.
I really do think there is some strong antibacterial effects at play with the UV, and salt water combination, not to mention the humidity which is great for dry skin conditions. I have heard of several peoples EC termorarly abating when going to different climates.