By their very nature islands are often unforgettable. Some were forged by volcanic eruptions, others thrust up by tremendous forces deep in the earth, cut off by floods or erosion, or torn from the nearest continent by the inexorable movement of the earth’s tectonic plates. Their stark beauty and peaceful solitude bear witness to the drama of their creation. In their isolation, they may have developed species, ecologies and even weather patterns of their own. Their inhabitants, too, are often unique: cut off to some degree from cultures. Whether distant or almost part of the mainland, they will have evolved their own lifestyle and customs.

Whatever island you may choose to visit, travelling to it is easier than ever. You can now fly to almost any country in the world in a day; in two, you can reach all but the most remote destinations. Within a mere 72 hours of leaving home you can find yourself at the very ends of the earth. I delight in the fact that for less than the cost of a plasma TV set it is possible to take a week or two off work and go somewhere truly stunning.

All it takes is the will. And it is in that spirit that we bring you this book. Instead of buying the TV set, you buy an airline ticket. Instead of going to work, you go to the airport. Instead of spending a week at your desk, you spend a week in paradise. Waking up to an early morning alarm, ready to head off to some far-flung destination, I often consider the simplicity of my options. I could switch off the alarm and stay in bed, or I can get up, make that familiar trip to the airport and be in the middle of nowhere tomorrow, eating noodle soup in Laos, drinking tea in Yemen or bathing with pilgrims in India.

Since Unforgettable Places to See Before You Die – my first book in this series – was published I have met or been contacted by a number of people who have been inspired by it. Some have given it to a partner as a subtle call to action. And at least one person, given it as a retirement present, has decided to try to visit every place in the book.

For this fourth title, my associate photographer Marc Schlossman and I travelled to all 40 of the islands featured in just 11 somewhat frenetic months. What I hope we have achieved is another snapshot of this beautiful planet that will encourage people to experience more of it, and to consider visiting some places they would otherwise never have considered.

At the start of the project I decided not to repeat any of the islands covered in the first three titles in the series. You won’t find the Galapagos, Santorini, Manhattan, Zanzibar, the Maldives, Cuba, Iceland, Ireland, New Zealand’s South Island, South Georgia, Aitutaki in the Cook Islands, or the islands of Australia’s Great Barrier Reef in this book, but in a sense they should be considered an extension of it. Instead, we have chosen to include such eclectic, out-of-the-way destinations as Sagar in India, Lamu off the coast of Kenya, Socotra in the Arabian Sea and even Rapa Nui (Easter Island) in the Pacific Ocean. Other islands, such as Madeira, Ibiza, Sicily or Bali, might seem more familiar, but we have tried to show sides of them you might be unaware of.

About halfway through this year of photography I learnt that my partner and I were expecting our first child. I found out in Botswana during my visit to the salt-pan island of Kubu. Since then I have looked at the world with fresh eyes, and it has seemed more fragile than ever. I wonder whether my daughter will have the opportunity to gaze upon the sights I’ve seen; whether she will see dolphins and elephants, baobab trees and unspoilt beaches. Will vibrant cultures still exist, or will the homogenizing effect of globalization and proselytising religions have crushed their individuality?

Some people think tourism endangers local cultures, but if it is done with careful consideration, it can both encourage and reward their preservation. While tourism can be a positive influence, it would be na´ve to believe there are no negatives. Islands are very susceptible to mass tourism, and to one of its latest trends in particular: huge cruise ships that enable people to travel through the earth’s less developed regions in a four-star comfort zone without ever coming into direct contact with their surroundings. Unlike the little ships that took us around Tierra del Fuego, and Svalbard in the high Arctic – two of our more far-flung destinations – these liners churn sometimes thousands of passengers around the world in an air-conditioned bubble.

There is a lot you can do to make the world a slightly better place. Remember that your holiday destination is someone’s home and that they would appreciate your respect, courtesy and a friendly greeting. Don’t avoid big hotels, but ask them about their environmental policies – preferably before you reserve a room. Throughout the world, many admirable people and companies involved in tourism have been caring for their environment and local communities for years, others are just jumping on the save-the-planet bandwagon for marketing reasons. Above all, travel softly and gently and engage with your surroundings. I have shaken so many hands over the past year, looked countless people in the eye and greeted them with a simple smile. I have been rewarded with unfailing hospitality, curiosity and generosity in some of the poorest, most distant places on earth.

Steve Davey, 2007