Way south of the mainland, Vietnam’s idyllic Con Dao Islands (population 6000-ish) are the perfect oceanic antidote to the feverish energy and punishing pollution that can afflict the nation’s booming mega-cities.

Vietnamese fishing boats on a tropical Con Dao Island. View from the pier in the direction of a beach with white sand. Colourful Vietnamese fishing boats in the Con Dao Islands

For decades the main settlement of Con Son was used by the French and Americans as an island prison for anti-regime activists and criminals. Several of these jails are now deeply moving, harrowing sights to visit. History aside, Con Dao is blessed with stunning beaches and rich coral reefs that represent the best diving in Vietnam. The islands have been declared a National Park, and there are rewarding rainforest hikes to remote bays.

Take a morning stroll in Con Son town

The islands’ tiny capital is a delight to explore on foot, with (almost) traffic-free streets, a couple of traffic lights (which don’t work) and a solitary gas station (which closes for a siesta). This is Vietnam in the slow lane.

Begin with an early morning stroll along the town’s spectacular promenade, with a horizon-filling turquoise ocean on one side and a roster of handsome ochre French colonial buildings to admire on the other. You’ll pass the old Gallic customs house where Camille Saint-Saëns composed his opera Brunhilde in 1895.

Family on a motorcycle ride past colonial house. Family on a motorcycle ride past a colonial house

Next up, take a peek inside Con Son Market, where you’ve the option of a local breakfast (think rice porridge or noodles) and a glass of drip-fed, treacle-thick Vietnamese coffee. If you’re thinking more along the lines of a cappuccino and an omelette, head to Infiniti Cafe & Lounge instead, which has an arty vibe and a great street terrace.

Discover the islands’ terrible past

For a good overview of the islands, their environment (the Con Dao are important nesting grounds for sea turtles and there are 11 endemic trees) and their role as a concentration camp, drop by the modern Con Son Museum. This will prepare you for a tour of the prisons themselves. Make sure to check Vietnam tour packages

There were once 11 jails. The largest was Phu Hai, where political rebels and criminals were herded together naked in the French period; today the dank rooms are filled with emaciated, chained mannequins. This prison acted as a revolutionary university for leaders of the People’s Army of Vietnam and Vietnamese Communist Party, many of whom were incarcerated here by the French and Americans.

Vietnam, province of Ba Ria Vung Tau, Con Dao archipelago, Con Son Island (Pulo Condor), Pulo Condor penal colony used from 1862 to 1975, called tiger cages cells where prisoners were kept The infamous Tiger Cages

The most difficult prisoners were singled out for particularly gruesome treatment in the infamous neighbouring Tiger Cages, where they were kept in open-roofed pens, beaten with sticks and doused with lime (which burns the skin). Over 20,000 prisoners died in Con Dao.

Reflect on the beach

After a disturbing look into Con Dao’s past, lighten your mood with a trip to the beach. Grab a scooter and buzz up to the north of Con Son island, past towering granite hills and fishermen’s houses wrapped in wild bougainvillea. Nestling in a niche in the coastline close to the airport is the glorious cove of Dam Trau, flanked by rocky promontories, blessed with soft pale sand and fringed by casuarina and pandan trees. Feast on ocean-fresh seafood (try the crab) at one of the shacks on the shore.

Beautiful Dam Trau beach in Condao island, Ba Ria province, Vietnam Beautiful Dam Trau beach

On the return leg you could drop by the uber-luxurious Six Senses resort (Angelina and Brad stayed here in 2011), which occupies a stunning sheltered beach, for a sundowner, or even a gourmet meal. Alternatively, dine in the family-owned Thu Ba in Con Son town for delicious Vietnamese dishes (including plenty of choices for vegetarians). The English-speaking owner will guide you through the menu and make suggestions.

Hike the national park

Drop by the National Park management office at 29 Vo Thi Sau, Con Son town and get a (free) permit for entering the national park. There are many trails but some are closed during dry season (November to February) because of the risk of forest fire.

A butler at the Six Senses Con Dao resort in southern Vietnam overlooks a green, mountainous landscape off the resort's grounds. Once a secluded prison island, Con Dao is now turning into a luxury tourism destination. The green, mountainous landscape of the interior is great for hiking © Aaron Joel Santos / Aurora / Getty Images

The two most popular are the hike to the rocky bay of Ong Dung (where there’s good snorkelling on a fine coral reef offshore) and the steep climb up to So Ray, an abandoned plantation with fine views over the islands – it’s now home to a large troop of long-tailed macaque monkeys (watch they don’t steal your lunch!). In the forest keep an eye out for other wildlife, including black giant squirrels and monitor lizards.

Dive Vietnam’s best reefs

The Con Dao islands’ reefs are unquestionably the best in Vietnam, with healthy soft and hard coral, and there are also a few wrecks to explore (including a 65m Thai freight ship). You can expect to see a good variety of tropical marine life: parrot fish, triggerfish and perhaps a turtle. The best conditions are between January and June but diving is possible year-round.

www.vietnameseprivatetours.com/vietnam-tours The clear waters around the Con Dao Islands provide excellent diving conditions © Chi My. Trung Hamaru. Vietnam / Moment Open / Getty Images

Professional dive schools include Dive! Dive! Dive!, a long-established operation run by Larry, who knows the seas around Con Dao better than his backyard. The Con Dao Dive Center is another great outfit. Prices are comparable whoever you book with: two-dive packages cost around US$140; snorkeling trips about US$40.

Getting to Con Dao Island, Vietnam

The islands are connected to the mainland port of Vung Tau by ferries (three to four times a week), but since the crossing can be very rough, conditions very basic, the journey long (12 hours) and cancellations frequent, most people choose to arrive by air. Vietnam Airlines and Vasco operate three daily direct flights (return US$150) from Ho Chi Minh City and Can Tho.

Source: LonelyPlanet