I do not know how to swim so never thought about trying kayaking. May be you can try Virtual Reality? I heard they have all kinds of things coming up in VR in a year or so. You can go around the places in VR, may be even kayaking, even if AS wont let you walk or fly.
On a serious note, I think you should take one step at a time. even after you get well and be fit for activities, kayaking might be too extreme, as it can be dangerous to even a normal persons joints, and it needs quick reflexes in your neck and arms. Every one has different expectations. But surely you will know what you can and cannot do, but my advice, is to go slow on yourself, once you are fit for activities.
Male, early 30s. AS diagnosed Sep 2015. HLAB27+
Current medicines: Omeprazole, Vit D3, Celecoxib(1 tab)/Zorvolex(2 tabs)(alternatimg between these two every week), Pyridoxine, Isoniazid, MTX(3 tab) every wednesday, on humira every two weeks since Dec 2015, Weekly Humira since June 18th 2016