Thanks for that quick reply, I’ll give those spots a try at some point, it’s good to get a rough location of where to start.
Luckily I’m not expecting much, I used to do a bit of volunteer research work back in the UK and on one of the routes we covered, harbour porpoise was pretty much all we would see. Those are along exactly the same lines of that very good description (tyre floating and disappearing). I kind of like the fact that some animals keep their mystique by remaining elusive.
I read about the humpback, that would indeed be a great sight in these waters.