'Most beautiful beach in Europe' is on island where people were once forbidden

As the jagged hole in the rocks approached, it was clear we'd have to duck inside the tour boat if we weren't to scrape our heads.

When we felt safe enough to look up again, we were deep inside the Blue Cave, where the water was indeed coloured indigo by the incoming sunlight. This was one of the highlights of an island-hopping cruise on a luxury 36-passenger motor yacht in Croatia.

One evening my wife Mandy and I ate lobster at a restaurant table made famous in the Abba film Mamma Mia! Here We Go Again.

It was on the island of Vis, one of many ancient ports lined with narrow streets opening on to wide promenades at the seafront. The weather was so hot, it was comfortable to have a romantic al fresco meal every evening before strolling back to the ship, sometimes with a gelato in hand. Not that long ago, this would not have been possible - after World War Two, the island was under the control of Yugoslavia, which turned it into a military base and prohibited all foreigners from visiting.

Vis is also home to Stiniva beach, which is almost completely obscured from view from both land and sea, surrounded as it is on almost all sides by a horseshoe of imposing cliffs. It was named the most beautiful beach in Europe in 2016.

Another day, I hiked into a national park on the island of Mljet and took a dip in a natural lake. Every morning on our trip we had a swim stop where I pulled on a snorkel to follow streaming shoals of fish in crystal-clear waters.

Our trip on the vessel called My Wish began in Split, Croatia's second biggest city after the capital Zagreb. This isn't how you imagine a cruise ship at all - its sleek lines look like something belonging to a millionaire oligarch.

From its pointed bow to the expansive open-air lounge areas at the stern, this 154ft-long, four-year-old craft gleams and shines with polished steel and clean white metal.

The main deck has a reception, four-table dining room and bar. Eight cabins are on the floor below and ten - with private balconies - on the deck above. Up top is a sun deck with a mini gym and hot tub and a steep set of steps up to another small area of loungers.

Each day begins leisurely with a buffet breakfast and a choice of eggs cooked to order.

After the swim stop, when some passengers went swimming from the rear marina, or used the boat's water toys such as paddle boards or kayaks, it was time for a three-course lunch, before sailing to a new island, either for a brief visit or to moor for the night.

Dinner is provided for two nights on board - the initial welcome party and a captain's dinner towards the end. All other evenings, passengers are free to make their own decision about where, what and when to eat on shore, choosing from either one of the ship's recommendations or visiting a bar and grabbing a snack like a pizza.

Most of the time the dress is casual both on and off board but there's a chance to pull on something special for the captain's farewell - the only night any entertainment is provided, in the form of a three-man accordion and guitar group who covered everything from traditional Croatian songs to pop classics.

From our embarkation in Split, where we did a walking tour of the Roman Diocletian Palace, we sailed to Trogir, often compared to a mini Venice.

The next morning we cruised past Golden Horn Beach - a spit of sand jutting into the sea - before arriving at the party island of Hvar, where we enjoyed a wine-tasting excursion.

Passing the Pakleni islands, we arrived at Vis, once a Yugolsav naval base that was off limits to visitors, where the Mamma Mia! sequel was filmed.

After visiting the Blue Cave on the island of Bisevo, we took a tour in Korcula, hearing tales of Marco Polo and an inspiration for James Bond - Sir Fitzroy Maclean - who lived there. If you enjoy a drink with a view, there's a cocktail bar in a tower where you can climb a ladder to look out across the city while your tipple is hoisted up on a pulley system.

On our final full day, the captain sailed us around the walls of Dubrovnik, which we later visited, staying into the evening when many other tourists had gone. The city, now better known for Game Of Thrones, still bears the scars of the war which consumed the then Yugoslavia in the 1990s.

The great feature of this trip is the flexibility. Though we really enjoyed our chats with fellow passengers over breakfast and lunch, it was lovely as a couple to search out a shoreside restaurant each evening for a table for two.

The Cruise Croatia ship moors so close to town that you can come and go as you please - and there's no pressure to take the included excursions. One day we skipped a visit to an oyster farm to relax on board - after all, it is a holiday!

The mix on our cruise was mainly Americans, with some Brits and Danish and South African couples. Our ten-strong crew pulled out all the stops, with the two cooks performing miracles in a small galley to provide a variety of food every day. Two other staff tended to the bar while others took care of the housekeeping and engineering duties.

In some ports, several boats docked next to each other, so you have to clamber through or around other vessels to reach shore - nine was the most I saw, with My Wish being the eighth.

This is cruising without queues, early starts, long coach excursions or crowded buffets - a small-ship alternative to the giants of the seas. You might think this was only for the very rich but a week's trip costs as little as £1,795, though you do have to budget for flights, port taxes, tips and meals out.

The parent company of Cruise Croatia is called Unforgettable Travel - and this trip certainly was.

• Cruise Croatia offers seven-night cruises from £1,795 per person, including breakfast, lunch, private transfers, all excursions and wi-fi. Flights and some dinners are not included. cruisecroatia.com
• More info at croatia.hr/en-gb