A trip to the heart of Gibraltar

This extraordinary beautiful cavern is remarkable for three reasons: the size of the main chambers, the profusion and variety of calcite formations, and last but not least - a lake of crystal-clear water, nearly forty yards long estimated to hold 45,000 gallons.

Since the lockdown ended on the Rock, scores of thrill-seekers have slowly been returning to this subterranean experience.

The guided tour typically takes about three hours and involves plenty of climbing, shimmying up and down ropes, squeezing through passages and tip-toeing your way around a small ledge to avoid falling into the huge crystal-clear lake.

Not to be confused with Saint Michael's Cave, which was once occupied by Neanderthal Man and now hosts concerts and other cultural events in its large auditorium, Lower St Michael's Cave was found entirely by accident during World War II, when the upper cave was being converted into a military hospital.

Peter Jackson MBE, 60, a Registered Freelance Guide, said: «The Royal Engineers required an operating theatre deep inside the cave and once they had done this, they then realised that they needed another entrance. So, blasting their way into this lower level, the floor collapsed beneath them and Lower Saint Michael's Cave was discovered.»

Peter, who grew up in Scarborough and moved to Gibraltar at the age of 28 in 1989, explained that most of the cave was then discovered by a young soldier named 0'Braithe.

He continued: «This Sapper realised he could see a bit of a gap and believed there may be a further chamber. So, with no training in conservation, he went down there and drilled through where he saw the gap and discovered the rest of the cave - some 90 per cent of Lower St Michael's.»

And it's a good thing he found it, as a visit will leave you breathless, but not from lack of oxygen!

Underground you'll find examples of almost all known cave formations, including stalagmites, stalactites, rim stone, helicities, columns, cave coral, flowstone, straws, curtains and two of only seven known 'painter's palettes' in the world.

So why is this an interesting cave to explore, according to Pete?

«Well, caving is a dangerous sport and Lower Saint Michael's Cave being roped and lit, allows you to visit it with a lot of the dangers already catered for. As long as you are relatively fit and active, you are open-minded to what you are willing to try, then this cave almost spoils people.

«The level of beauty within it, is seldom matched. I've been caving all my life and I can't think of another cave that matches it for beauty.»

As for who would enjoy a tour of the cave, Peter, who has taken thousands of people on underground tours in Gibraltar's tunnels and caves, including Princess Anne, football legend John Barnes and the former MP Geoff Hoon, added: «It is a challenge, but the cave is do-able for most people over 10 years old that are physically fit. We don't put an upper age cap on it, but you do have to be sensible about your own abilities. No guide will force you to do anything that you don't want to do on the way in.

«But you do have to get out!» he joked.