Chichester Harbour is an excellent place on the south coast to go canoeing. There are various arms, or creeks, which you can explore by kayak or canoe, and numerous places to launch from.
Before paddling you should be aware of the tides, which can move rapidly, and the wind, which can make paddling different and waves large. You also need to be aware of and avoid the boat traffic which can be moving faster than you think. The entrance channel has a very fast running tide race, so should be avoided by all except experienced canoeists. However, the top end of the creeks above Itchenor and near Bosham are more sheltered.
There is much birdlife to see, and if you're lucky you will see seals too.