I have just returned from holiday in Cornwall .I was exploring the cave in the Townroath vugga from the beach , & went up through the waterfall coming out of the adit & the level beyond was wonderful ,I was only able to explore about 300yards up it as the tide was coming in ! There was evidence that other people had been there recently & I wondered how far in the level went ,was it safe to explore further [I was with my son so was more carful thean if I was alone!].I'm no expert just an enthusiastic amateur bred on exploring mines in the pennines & the lakes