I know they’re out there. Somewhere among the small white-capped waves being whipped up by a brisk northwesterly off Flamborough Head there must surely be a school of harbour porpoises.
A couple of weeks ago two dozen of them were spotted from the cliff top at Old Nab, to the south of Staithes, and other sightings - either as individuals or in pairs - were reported at Bempton.
But on this particular day they remain maddeningly elusive to me out there in the wide blue expanses of the North Sea, and after a couple of hours of raising and lowering binoculars and optimistically re-targeting my telescope I mutter something about needles and haystacks and give up.
For much of the time, sea-watching for cetaceans - whales, dolphins and porpoises - can be pretty unrewarding on the Yorkshire coast, but every now and then you get lucky.
That is especially the case in August, which often seems to provide the greatest number of sightings in UK coastal waters and is the reason why the National Whale & Dolphin Watch was held earlier this month.
The school of harbour porpoises near Staithes was Yorkshire’s highlight of the week, but there were numerous other sightings of the 6ft-long species from Whitby and all the way down to Hull in the Humber Estuary. Also known as the common porpoise, it is fairly abundant in the North Sea, where the population is estimated at approximately 385,000, and besides being the cetacean most likely to be seen skipping through the waves it also turns up in fishermen’s nets.
On occasion it is even found inland, with sightings at Hempholme Lock on the River Hull, some 20 miles from the Humber, and on the River Ouse at Naburn Lock to the south of York.
Too often, however, the public’s knowledge of the presence of cetaceans is through strandings of dead or dying individuals or groups on the shore at places like Robin Hood’s Bay and Spurn.
And this is especially true of the bottle-nosed dolphin and of the increasing numbers of whales from the Arctic which are being brought south into the North Sea by changes in currents as a consequence of global warming.
Used to swimming in deep oceans, pods of whales are now thought to be getting somewhat confused when they meet shallow inshore waters and tides.
Fortunately, two minke whales that were spotted off Whitby a few weeks ago kept well away from land.
Others of the same species have been sighted this summer off the east coast, from Filey, Cayton Bay and Burniston near Scarborough - some of the 10,000 minkes that are estimated to populate the North Sea at the moment.
Thanks to experienced watchers in Yorkshire, we know that there is plenty of life out there.
More than other forms of wildlife, close encounters with whales, porpoises and dolphins are arguably the most rewarding of all.
To see a pod of whales arching through the sea anywhere is truly wonderful, and finding a 35ft-long sei whale unexpectedly surface next to my boat off Flamborough a decade ago was, for me, one of those experiences that will never be forgotten.