Crystal Cave, Bermuda

In 1905 two twelve-year-old boys, Carl Gibbons and Edgar Hollis, went after a lost cricket ball and found a cave instead. It is around 500 metres long and 62 metres deep, in Hamilton Parish near Castle Harbour.

What happened next would not be allowed today. The Wilkinson family had owned the property since 1884, and when they heard, Percy Wilkinson lowered his 14-year-old son Bernard into the hole on 140 feet of rope tied to a tree, with a bicycle lamp for light. It opened as an attraction in 1907.

The cave is a record of changing sea level. It formed when the sea stood lower than it does now, and as the water rose many formations that had grown in air were drowned. The bottom 19 to 20 metres are below water level today, so you walk a floating pontoon over water clear enough to see the submerged formations continuing below you.

The wider setting explains it. The limestone around Harrington Sound, just to the south, is riddled with subterranean waterways, and the sound drains through them into the Atlantic. Crystal Cave is one of those channels, and it is known for stalactites, stalagmites and deep clear pools, though some crystal formations were broken by earthquakes long ago.

A visit normally takes in neighbouring Fantasy Cave as well, which is deeper at 88 steps down. Fantasy reopened in the summer of 2001 with its pathways rebuilt and lighting replaced.

Fantasy Cave has had a stranger history than its neighbour. It was found and opened at about the same time as Crystal Cave and then closed by the owners in the 1940s, staying shut for some sixty years before it was brought back.

Both caves sit at 8 Crystal Caves Road on Wilkinson Avenue and are owned by the local Wilkinson Trust, still the same family name that held the land in 1884. They are reachable by the bus that runs between Hamilton and St George's, by taxi, and by the motorbikes and bicycles that Bermuda runs on. Outside is a subtropical garden of palms and flowering trees.