As with any other sport or game, there is a certain amount risk involved such as:
Minor injuries including cuts, bruises, knee and shoulder sprains and strains
Risk of diseases from harmful microorganisms such as Hepatitis A
Harm from the unpredictable environment such as sewage, sharks, jellyfish & stingray stings, coral reefs, rocky seabed and strong waves.
Other dangers including drowning, collisions, rip currents, etc...