This is a hornet. It is a large relative of the common wasp and although it looks fearsome it is apparently much less aggresive than a common wasp. I don't like either but I do accept that both are important pollinators and pest controllers so reluctantly I welcome them into our garden This one was hovering over the pond which is typical behaviour. They collect water in their mandibles to either consume or take back to their nests.
@carole_sandford I remember them well in Cyprus. I was stung by a hornet out there and it left the sting in my arm. Bloody painful.