Having Irish heritage as well (which shows in me but not my brothers), I burn very easily. Floating at the water surface is a double-whammy, as not only do we get direct rays from the Sun, we also get reflected rays off the water. I have a full-length lycra skin for sun protection, along with gloves (regardless of how warm the water might be), and I wear a lycra hood to cover the neck and ears, as well as help keep the hair and beard out of the way while diving. Any exposed skin will get a sun screen, but I did buy the eco-friendly stuff from the LDS, after hearing of potential harm to marine life from normal sunscreens.
With skin cancer on the rise, and the very real potential for melanoma to metasticize into deadly internal tumors, awareness of our UV exposure is vital. According to the Mayo Clinic, the top 12 risk factors for skin cancer are:
Fair skin
History of sunburns
Excessive sun exposure
Sunny or high-altitude climates
Moles
Precancerous skin lesions
Family history of skin cancer
Personal history of skin cancer (as in, having had it before increases the odds of getting it again)
Weakened immune system
Fragile skin
Exposure to environmental hazards
Age
I have 9 of those. I watch my sun exposure very carefully. In fact, I get to see my dermatologist next week, for my twice a year check up and freezer burn.