From Longman Dictionary of Contemporary Englishwater skiingˈwater ˌskiing noun [uncountable] DSOa sport in which you ski over water while being pulled by a boat —water ski verb [intransitive] —water skier noun [countable] Tracy was a keen swimmer and water skier.
Examples from the Corpus
water skiing• Leisure activities still take place here although they are more likely to be water skiing, wind surfing and sailing rather than bathing.• One hour water skiing and scuba diving at sea.• I want to go board-sailing, maybe do a little water skiing.• She went water skiing while Prince Charles went windsurfing. 