Harley likes tidying up stetches of water. If you throw a stick in a pond he has to bring it back - so far so normal. But he also brings back any sticks, empty bottles or cans that he might come across by accident. In fact he refuses to get out of the water without finding something to fetch. It can be a long and tedious process 
Again.... not abnormal I guess. But on holiday he insisted on 'rescuing' the kids bodyboards - with or without the kids on them - by grabbing the loose wrist straps and towing them back to the shore. V odd. He did it time and time again to the sound of kids laughing and/or protesting loudly! There will be several people who holidayed near Fowey this summer with footage of the amazing ferrying dog on their camcorders 