Three boatloads of people will be allowed to explore tunnels and crumbling fortifications

Every nook and cranny teems with history. The tales of war, adventure, death and crime are myriad but for 30 years the people of Plymouth have only been able to gaze across at Drake’s Island – but not set foot there.

But on Sunday three boatloads of visitors will make the short hop from the Devon city to explore the crumbling fortifications, the bramble-covered barrack buildings and its mysterious tunnels.

The island in Plymouth Sound has been off-limits since 1989 – when an adventure centre on the island closed down – but is now being developed as a luxury holiday resort, and before building work starts, people have been invited to buy tickets – the proceeds of which are going to a local hospice – to join exclusive tours.

Demand for the 210 tickets for Sunday and a second trip in May was huge. They were snapped up within minutes and St Luke’s Hospice Plymouth, which will benefit from the proceeds, reported that its website received almost half a million hits during the sale period, not just from Plymouth people but from fans of history and islands from across the UK.

Robert Maltby, the head of communications and marketing at the hospice, said the island was important to the people of Plymouth.

“It’s an intriguing place,” he said. “If you’re a Plymothian it is right there in front of you all the time. It’s a major piece of the city’s history and everyone wonders what it’s like.”

The 2.5-hectare (6.5-acre) island has been a place of pilgrimage, a refuge, a fort, prison and – until the late 1980s – the site of the Drake’s Island Adventure Centre.

Maltby has had a preview of the island, taking a trip there to take photos for the ticket sales. “I was taken aback by how good a condition many of the buildings are still in,” he said. “Some are overgrown with brambles but the brickwork has somehow stayed looking pristine.”

His favourite part was the tunnels, which have been used to store ammunition and other goods over the years. “They were pretty amazing,” he said.

The island’s warden, avid historian Bob King, will lead the tour. Over the years his role has included guarding the island and keeping its shoreline clean.

But he said: “The best part of my job is researching the history of the island and sharing it with as many people as possible.

“Although the fortifications and how they have been used and defended Plymouth over the centuries is fascinating, what brings the history alive are the personal stories of the people on the island.”

The island was initially known as St Michael’s – named after a 12th-century chapel built there. It is only in more recent times that it has been known as Drake’s Island, after the Elizabethan sea captain.

In the 16th century, as defending Britain’s shores became more important, the chapel was demolished and artillery towers, musketry walls and barracks were constructed.

At one point it served as a prison but as the naval dockyard in Devonport grew, its fortification and armaments were beefed up to protect the fleet.

During the second world war it was a minefield control post and if there had been an invasion explosives would have been detonated from the island.

It has also been a scene of tragedy. In 1774 a local shipwright and carpenter, John Day, designed a wooden diving chamber and made a bet over how long he could stay submerged. He perished in the adventure.

Drake’s Island has been a magnet for all types. Queen Victoria sketched it and in 1957 a bunch of schoolboys “invaded” it and claimed the island for Plymouth. They were arrested by the guard, given breakfast and then taken back to the city for a double maths lesson.

In 2005, anti-nuclear campaigners set up a peace camp and declared the island a nuclear-free state. They followed in the footsteps of brandy smugglers, who used the island as a stopping-off point.

The island was bought last year by a local businessman, Morgan Phillips. His hotel plans include a glass elevator that will whizz guests up from the jetty. The governor’s house, barrack block and “ablutions building” are to be linked together with a smart extension.

Another plan is to open a heritage centre to tell the story of the island and Phillips is working on a scheme with the Plymouth-based Ocean Conservation Trust to open up the island for children to learn both about its history and the seas around it, which are important for seagrass, sea horses and seals.

Roger Maslin, chief executive at the Ocean Conservation Trust, said he was delighted at the new possibilities. “It is an amazing place,” he said. “This is a great opportunity to get them out there in the field and learning with some first-hand experience of the ocean.”