Spent a bit of time in the summer looking at various bits of the coast & recording lots of new sites. Probably the most interesting however was what Gus Horsley called Sealhole, however it is nowhere near either Sealhole Cavern or Sealhole Mine which are much further towards St Agnes Head. The Sealhole's location is well known both amongst locals & from mine plans & records.
Suggest the site by the old harbour walls could be called Luna Caverns on the basis of the nearest mine name (Wheal Luna). It needs a proper survey as a quick recce (without proper gear & on a rising tide) shows it to be suprisingly complex. However it looks like it will be a long time before conditions allow another visit!

Hi Alasdair

Have you got an NGR for Luna Caverns, Seahole etc?

Apologies for the duff information, I was misled by one of the locals. 

For interest: Wheal Lunar

I made a solo visit to Luna Caverns at the low spring tide this New Year, and a very impressive
and photogenic spot it is too ! I assume that there must be a lode in there somewhere otherwise
why would the miners have gone to the trouble of driving a level into a sea cave ?

The impression I have from the surface exposures is that it's a series of small intersecting lodes which collectively quite wide but of limited horizontal extent.

Luna is an odd and interesting mine that is probably holding alot of secrets, oh and thats me in the blue overalls in the video lol

Please, has anybody got an NGR doe Luna Caverns and Seal Hole?   

Aditnow gives Wheal Luna as SW720517 and SealHole as SW714514 if that helps!

Many thanks, will add to the book...

I am not sure if there are any actual mine workings within the cave, the sections of man made tunnel seem more likely to have been access routes around the cliffs perhaps associated with the Hall and Parlour entrances (which are the area called Old Key, the site of an earlier unsuccessful attempt to establish a harbour, a bit north of the eventual longest-lived harbour.

https://www.youtube.com/watch?v=qTaUK-oS1fM

Luna caverns on high tide, entered via the tunnel