A nice lightweight canoe.
If the the thought of loading your bargelike canoe on the roof makes you groan, you're not going to go paddle very often. A light boat that's easy to load has meant a lot more time on the water. We've had a lot of nice after-dinner evening paddles because it's not a big deal to load up and go.
Nice canoe and kayak paddles make a day on the water much more comfortable.
A bike fit. Paying to be professionally fit made a huge difference in comfort and efficiency.