One reason for the cramps on the beach might be the cold temperature of water in contrast to the beach itself. The second source is the heat. When the person faces a sunburn effect, it may also challenge the heat cramping. The muscles close to the injured regions cramp and hurt too much. It may feel like they are temporarily paralyzed. Try to drink more water when it happens. Do not apply butter to the injured regions as this method does not work as it was recently proved. Apply special sprays and creams only if approved by your doctor. Try chilly water compresses instead – this is a time-tested method of sunburn treatment!