You can hire old fashioned Canadian canoes from the Outney Meadow Campsite who also have bikes for hire. We'd recommend this stretch of the river if you are a beginner or nervous about canoeing, or have small children on board.
Rowan Craft near the Locks Inn at Geldeston is great if you are a bit more confident about canoeing (though there's not a lot to it!) and has the benefit of allowing you to paddle to the pub and moor up for some refreshment before heading back again.
If you like your canoeing slightly more adventurous, try Iken Canoes south of us near Aldeburgh - a beautiful spot for exploring by canoe.