Drivers are reluctant to cross the ancient causeway that connects the island to the Essex coast for fear the salt water will rust their engines.
But that's not a problem for most visitors - who jet in by helicopter.
The island is a rehab centre where burnt-out rock stars, high flyers and celebrities seek treatment for mental health problems, addiction and eating disorders.
And the patch of lawn that doubles as the island's helipad is getting busier - The Causeway Retreat says the recession has boosted its business as stressed-out executives follow in Amy Winehouse's footsteps and check in to recharge their batteries.
"We've been at max capacity for the past year," says the retreat's general manager Mark Gregory on a tour of the island.
"The recession isn't hurting us, I say it with sadness - it's aiding our business."
'Tip of iceberg'
The Causeway Retreat estimates that it has seen a 60% increase in clients from corporate sector in the past nine months.
 |   You can be a captain of industry but it doesn't mean you have life skills  Mark Gregory, The Causeway Retreat |
"You can be a captain of industry but it doesn't mean you have life skills."
Housed in clapboard cottages and a larger manor house, the rehab centre exudes a laid-back charm on a sunny June morning.
The bedrooms are stylishly decorated with four poster beds, flat screen televisions and claw-footed roll-top bathtubs that would not be out of place in a five-star hotel.
But the wellington and hiking boots scattered at the door give a more homespun air. Its gym is housed in a row of old stables, and a yoga studio is hidden away in a wooden outhouse.
The retreat's one big concession to its celebrity clients is a recording studio that once belonged to Bob Marley, though the retreat won't divulge whether any hits have been made there.
'Wolf pack'
Brendan Quinn, the retreat's chief executive and a former psychiatric nurse, says that its corporate clients come chiefly from the world of investment banking and law, and are predominantly female.
 The retreat's secluded location makes it popular with celebrities |
Clare (not her real name), a finance director at a financial services firm in the City, spent a month at the retreat in November last year.
"It did all come to a head when the financial crisis really hit," the 50-year-old executive says.
"I think that tipped me over the edge. I was working even longer then and drinking a bit more than I should."
"It was like being a woman in a wolf pack."
Her stay at the retreat triggered a complete change in lifestyle. Although she returned to her job briefly, she later quit and moved away from London and now does the accounts for a small firm.
Like most of the retreat's clients, who must all sign a confidentiality agreement, she is keen to preserve her anonymity and is nervous about speaking to a journalist.
"I thought it a sign of weakness to tell people. My father was a services man - he said you make your own bed and lie in it."
Realistic solution?
Ben Pimlott, senior policy advisor at the Chartered Institute of Personnel and Development, said while rehab might work for senior managers, it is not a realistic solution for the vast majority of us.
"Line and middle managers are under as much pressure as board level directors," he says.
 In the past, the retreat's clients have hailed from the music industry |
Stress is the biggest cause of long-term absence for non-manual workers, and workplace absence on average costs a company £666 per employee each year.
Companies do take the problem seriously, but they could do more to safeguard employee well-being, Mr Pimlott adds.
"Employers can depend on employees to go the extra mile in a recession, but once things pick up people will vote with their feet," he says.
Ruth Spellman, chief executive at the Chartered Management Institute, agrees that managers are under increased pressure, with four in 10 British managers not having yet booked any holiday this year.
"Managers are easy targets when times are tough, they are after all the face of an organisation and so can make easy targets.
"So, it is perhaps unsurprising that given the increased pressure managers are under because of the recession that they may be paying the price when it comes to their wellbeing," she adds.
Expansion plans
To cater for the growing demand from the corporate sector, the retreat is expanding.
It plans to increase the number of rooms and cottages available on the island to around 40 from 23.
Mr Gregory says the wider availability of private health insurance will make the retreat more accessible, and not just the preserve of celebrities and chief executives.
"Society is more at ease with mental health problems and it's more common for companies to have good private health care insurance.
"The attitude among companies is that we pay for it, we may as well use it."
But at around £10,000 for a week's stay, no matter how seriously companies take workplace stress, a stint in luxury rehab is likely to remain a genuine option only for a few lucky high flyers.