Missed your post unfortunately & hope the trip went well, but if you're planning another visit then a few thoughts.
Easterly is the one to avoid in that area.
Turn right out of Porthkerris pass Porthoustock, Godrevy beach, Dean Quarry & Lowland Point & you're round into Coverack bay.
I've boated out of Coverack as a summer holiday for 50+ years on & off.
Paris Hotel in Coverack next to the harbour food & drink, coffee etc &
Not aware of any issues with visitors popping into Coverack harbour for a short stay during the day, but it is a drying harbour.
Harbourmaster Chris Pryor works at the Windsurfing Centre & is normally there when they're open.
Safe shallow sandy beach.
I plug close in for bass along the side of Lowland Point, shallowish with rocky bottom & round into Godrevy beach & Dean Quarry area. Usually drifting.
Westin Sandy Andy 22gr/13cm usually effective if they're around - last summer they weren't!
Freelining frozen sandeels is also effective.
I've not fished further round towards Porthkerris than Porthoustock as if I'm out for the day I'm either out onto the whiting ground or Black Head & along its side towards Kennack Sands, the whole of the latter area good close in for bass.
Can't comment on diving/snorkelling as it's not something I do.
Porthkerris will look after you & likely give you all the info you need & if you haven't already got it Navionics Boating app which I've got on my phone. The overlays are really something else!
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