IT'S the school summer holidays, when families flock to popular Mediterranean hotspots, vie for towel space on beaches and jostle for swimming space in seas teeming with inflatables.

No such jostling on the Croatian island of Brac (pronounced 'Bratch'), separated from the mainland by the Adriatic, a 45-minute ferry ride away from the heat and madness of Split.

It's one of the unspoilt gems of the archipelago, a glorious mixture of limestone hills, ravines and gorges, whose beaches in the capital Supetar have recently been recognised under the White Flag programme for ecologically clean sea water.

There are crystal clear bays, coves and immaculately clean pebble beaches all along the quiet coastline of the island, the largest of the central Dalmatian group of islands and the third largest in the Adriatic at 40km long and 12.5km wide. And the vast majority of them are quiet.

You can island hop, taking day excursions to the party island of Hvar and to sleepy Solta, but there's plenty on Brac to keep the family amused for at least a week.

Here's a selection of top quiet coastal spots which the whole family can enjoy...

Splitska

Around 15 minutes' drive from Supetar is the sleepy harbour town of Splitska, where small motor craft and yachts share space with families swimming and fishing on neighbouring rocks.

Shaped in a horseshoe on the winding, rocky coastal road in the north, with beautiful traditional stone houses cut into the rock face, it's so clean that young locals happily swim off the harbour wall.

It's the port from which Roman settlers sent the mined stone used to construct the Diocletian Palace in Split, and the stone has also been used on the White House in Washington and important buildings in Europe. Culture vultures should head to the 13th century Church of St Mary and admire the 16th century citadel.

Murvica

On the south side of the island, around 38km (a 50-minute drive) from Supetar, this stunning white pebble beach is a short stroll from the busier and more famous Bol, but give me Murvica any day.

It's a bit of a hike to get there, as you have to park at the top and then walk down a fairly steep, rough walkway - not suitable for buggies - but when you see the azure sea as you approach, you'll know it's worth it.

There's plenty of shade from the overhanging pine trees and, while you will inevitably bump into a few other visitors, the sizzling sound of cicadas will drown out any noise of tourism.

Take respite in the Seven Olives, the only bar on a nearby terrace, where you can sit in a deck chair enjoying a plate of calamari under the olive trees or shelter under the wicker awning, overlooking the stunning bay.

Boboviska

This gorgeous hidden harbour on the west coast, around 20 minutes' drive from Supetar on the main road, has a population of only 450 and has become a haven for rich Russians with serious yachts who buy or rent the stylish hillside houses and apartments.

I suspect the concrete platforms from which visitors swim and sunbathe along this stretch of harbour and further around the promontory beyond are part and parcel of the rentals, although we plonked our towels down and weren't moved on.

Its name is derived from 'Bob', which means broad bean in Croatian and is one of the main crops grown there, along with artichokes. I also see peach and almond trees following the coastal path on foot.

Top tip: Park in the little car park at the entrance to the village. If you drive along the harbour on the narrow road, there is nowhere to turn around and you'll end up having to reverse out, with the harbour wall on one side.

Lovrecina

Perfect for families with young children, Lovrecina on the north coast, 10 minutes east of Postira, is the only sandy beach on the island, a haven for those who love making sandcastles and paddling in the shallow waters. It's accessible by road but much more fun by boat. Hire a six-seater traditional Dalmatian boat from Supertar (with the addition of a 5hp outboard engine on the back) and you can be there in half an hour. Boat rental is around 450 kn a day (£45) including fuel, and you can take it in turns to steer. If you want a beefier engine, you'll need a boat licence.

Moor up in the bay, swim to the sandy shore and enjoy a drink in the modern bar on a terrace above the beach, bordered by local limestone walls.

Zlatni Rat

The island's most famous beach, a long triangular spit of pebbled land sticking out into the sea like an enormous wishbone, which changes shape depending on the tide, is featured in virtually every Croatian tourist brochure. Adrenalin junkies can get their fix of watersports, from pedalos to parasailing, or inflatables crashing through the waves behind souped-up speedboats.

There's an air of cool about this slightly more sophisticated resort, where beachside shacks sell smoothies and crepes, and couples enjoy cocktails on decked bars adorned with wicker sofas under cream-coloured parasols.

While it's considerably busier than all the other bays, it's still pristinely clean. Snorkellers are unlikely to find plastic bottles and other eyesores at the bottom of the sea

Top tip: Avoid paying top dollar for loungers and umbrellas. Sitting in the pine-clad woods at the entrance to the beach is much cheaper - and you're closer to the bars.

TRAVEL FACTS

Hannah Stephenson was a guest of Thomas Cook (www.thomascook.com/holidays/croatia; 0844 412 5970) who offers seven nights at the 4-star Sentido Kaktus in Supetar from £1,090 for a family of four, on an all-inclusive basis. Price based on two adults and two children sharing a family room and includes return flights from London Gatwick on October 6, 2016. Regional departures also available.

Skyscanner (www.skyscanner.net/carhire) offers car hire in Croatia from £6 per day in May.