Mariella Frostrup relives her childhood holidays on Dinish Island

Inhabiting your own world is a perennial impulse of childhood, and on an island, half the work has been done for you. From the age of eight, the tiny Connemara outpost of Dinish, in County Galway, was our universe during school holidays. Three square miles of peat and bog cotton, with caves and white sand beaches, where golden grasses shuddered in the sea breeze and the boom of the Atlantic meeting land made our tiny smoke-filled bothy seem all the cosier when night fell.

Breakers rolled in from North America, the terns dive-bombed us to protect their nests and we swam in giant rockpools full of seaweed that we reinvented as the greasy locks of a sea monster. On the leeward coast, we skewered jellyfish washed up on the sand, terrorised giant crabs among the rocks and took home our trophies for the pot.

A narrow channel of water separated us from the mainland, enhancing our sense of having been cast adrift and our undisputed sovereignty over our small world. Without a boat, we were accessible only during the full moon, when the exceptionally low tide facilitated a frenzy of razor clam harvesting on the uncovered seabed. We felt isolated and powerful, a bit like Kim Jong-Un, ruling over our patchwork green domain.

Since those unfettered days of feral freedom, I’ve remained compelled by such inaccessible outposts, continuing to revel in that childhood fantasy of being cut off from the world. The strange mushroom-shaped Rock Islands of Palau, Micronesia, where I floated among the harmless gelatinous bodies of jellyfish in an inland sea which, having been stranded for millions of years, had lost their sting.

The rocky peaks that dot Ha Long Bay in Vietnam, where a visit is only possible by kayaking through tunnels in the rock face, into the soaring interior to find yourself in a solitary oasis where the silence is broken only by birdsong. And let’s not forget the luxury islands that dot the globe, enticing temporary escapists to enjoy the ultimate in privacy. My first visit to such a spot was the tiny heart-shaped islet of Mnemba, off the coast of Zanzibar, where windowless makuti huts, ruffled by gentle sea breeze, offered rustic accommodation at a price.

Even more off the beaten track is Song Saa in Cambodia, so remote that only the stars lit the sky as you stared out into the uncanny darkness and imagined yourself alone in an empty world. A couple of years ago, during a stay in Ireland, I took my own children back to my old playground for a whole perfect summer day.

The colours were more Caribbean than grey Atlantic; the calm turquoise sea and dazzling white sand more Grenadines than windswept Connemara. We picnicked on the beach then clambered over dry stonewalls to reach our old cottage, where we were all briefly silenced by the sight of the tumbled-down walls of our one-time home.

As the kids swam in the tempting but icy water, fled shrieking from the still raucous terns and floated among the purple and orange seaweed that once so terrified my siblings and me, the 40 years since I last set foot there evaporated into the briny air, bringing a tsunami of memories. In the intervening years, I’ve travelled far and wide, but I’m still never happier than when I can walk the entire perimeter of my domain and enjoy the sensation of inhabiting a world small enough to be instantly familiar.