A lot of the time these landing sites / buildings are a bit further inland. At the beach there is usually only a buried armoured cable leading to a concrete slab or something where it connects to underground ductwork.
If you're interested in that and have an hour of time there is a youtube video[1] of a local tracking these down around the Cornwall area.
If you're interested in that and have an hour of time there is a youtube video[1] of a local tracking these down around the Cornwall area.
[1]https://www.youtube.com/watch?v=K_nnUbX7uuQ