Minecraft wiki entry for Combat, associated text: Attempt to release the fishing rod while Riptide is still in effect. This will ensure that the player pulls them up.
If the player doesn't have Feather Falling, land in a water source. This will make sure that the player takes as little damage as possible.
Use this as a killing method. Not only does it make players look cool, it means they won't have to do this multiple times.