Are you going to be kayaking on a small lake, a pond, a river or coastal area? Why do I ask? Because it will matter a lot when it comes to choosing radios.
If you are going to be kayaking anywhere there is Coast Guard or any commercial marine traffic, then you need a “Handheld Marine Band Radio”!
I’m assuming your normal radio contact would be with others in your party so they need to have the same radios. If you are kayaking in an area where there is not typically any Coast Guard or Commercial Marine traffic then you may be better served with FRS or GMRS radios.