Dyna Diver was a kind of educational toy where you squeezed a plastic bottle to manoevere a diving bell to pick up treasure and drop them in a basket. I had two of them over a number of years in the mid 70's. It wasn't as easy as it looked either.
The arms to pick up the treasure on Dyna Diver were a bit trigger happy and the treasure was pretty flimsy when it came to grabbing it. A good toy for those rainy Scottish Caravan holidays! The bottle would split in the end. I'd love to get my hands on another one for old time's sake!