It depends which water sports you want to do, and at what level. You may need specialist extreme sports cover for more dangerous activities like freediving, jet-skiing or swimming with sharks. And there’s a big difference between kayaking on a calm lake and taking on a grade five white-water river.
Check your policy carefully to see if your activities are included as standard, or if you need to buy additional cover.
Although it may well cost you more to add extra cover for extreme sports, the risks involved mean the likelihood of a claim is higher, so it could be worth it for peace of mind.