There may be some diseases out there we don't even know. Stone mentions a Navy diver who claims he contracted the flesh-eating streptococcus bacteria recently in San Diego waters, though experts from the Center for Disease Control say the possibility is highly unlikely. Nonetheless, epidemiologists agree that new, drug-resistant diseases are appearing almost daily, and old diseases such as cholera and tuberculosis, once though extinct, are reappearing. Another problem is that one can't assume that surfers will act in their own self interest. There is already a high risk factor inherent to the sport.
Many surfers regularly chance drowning.
Ironically it is surfers, more than anyone else in the ocean, who should be the most concerned. There is very little dilution of pollutants within the surf zone, according to Oceanographer Mia Tegner of the Scripps Institution of Oceanography. Polluted waters aren't always obvious. Surfers shouldn't count exclusively on posted warning signs to deter them from contaminated surf. Though sewage treatment facilities are required by law to report leaks and spills, such problems aren't always immediately identified.