WHEN I WAS RESEARCHING for my previous novel, Greek Island Escape, I was lucky enough to spend a few days on one of my favourite Cyclades islands, Syros. With its natural harbour and skilled boat builders, Syros is proud to be a working island. The capital, Ermoupoli, has the grand Miaouli square, paved in marble and surrounded by fine mansions. This is the best-preserved neoclassical town in Greece, where wonderfully ornate churches and delightful, white-washed chapels stand shoulder to shoulder. Built on a steep incline overlooking the port, Ermoupoli is dominated by its crowning glory, a magnificent monastery built on the summit of its highest hill.

I enjoy the larger Greek islands, Crete, Rhodes, Santorini and Mykonos – some of my books are set on them – and I try to visit them most years, but I am also fascinated by the lesser-known islands. While I was on Syros, I came across a day return ferry to the small island of Kea. This island was new to me, so I ordered a frappé at a nearby café and googled Kea on my laptop. Half an hour later, I could hardly wait to buy a ticket.

I had discovered that Titanic’s larger, grander and slightly younger sistership, the Britannic, lay on the seabed just a few kilometres away. All nine-hundred feet of her. I couldn’t believe this wasn’t more widely known – it was news to me. As a child, I was enthralled by BBC TV sea life programmes involving the great Jacques Cousteau, and captivated by the adventures of Hans and Lotte Hass. It is difficult to recall that they were in black and white, because I always remember them in glorious colour, such was my childish imagination. Those fascinating underwater scenes came back to me as I stared out at the inviting Aegean, under a sky almost too blue to be real.

The next morning, I boarded the ferry from Syros to Kea. On the top deck, taking pictures as we approached Kea harbour, I noticed an excited group at the railing and, on investigation, saw a young turtle heading the same way. What an amazing beginning.

I planned to do nothing but sit at a harbourside café, think about the wreck of the Britannic, and soak up the atmosphere (and the sun).