Goodwick Beach, Fishguard to Newport Beach crossing 12 - 17km (depends on initial setup - see descriptions) of open sea (route of the Fishguard Bay Ocean Race)DownwindfunDownwindable.com, practice run video, video2
North Stack video this video is a good introduction to North Stack (but seek out good local knowledge!) though it does not really look at where and how to paddle the tidal race as a surfskier.
Rhoscolyn Head
South Stack
Penrhyn Mawr Tidal Race - (Inner, Middle and Outer Race - increasingly faster and larger waves) famous among sea kayakers, advanced paddling (at least when it looks like these videos) multi-directional waves, can be very technical and challenging (more tidal races). Obviously (from the videos) some skilled sea kayakers with bombproof rolls can handle the race in severe conditions. We do not currently (2020) have reports yet of paddle runs and conditions that safely favor various skill levels (if any) of surfskiers. This may be a tidal race that is simply too full of counter currents, intersecting waves, whirlpools, etc. to allow many if any surfskiers to thrive on its waves. In other tidal races such as Deception Pass, surfskiers have already spent significant time learning angles of entry and exit, zones for surfing without excess turbulence, and weather and tide condition sets that are likely to favor their skill levels.
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