Five o'clock in the morning is no-one's favourite time of day, unless you're just coming home from a night out – or happen to work in the fishing industry. So it's no surprise that, as the first pinky-grey fingers of dawn steal through the sky over the South China Sea, the waters come alive with bobbing wooden boats, edging closer to the shores of Kep beach to start unloading their profitable cargo.

The day before, the fishermen will have patiently baited a series of bamboo traps with dead fish, and prayed to Manimekhala, goddess of the ocean, that overnight they'll have success.

They needn't worry. For as long as people can remember, there's been an abundance of blue crab living and breeding in these waters, which feed off a particular type of seaweed that grows here, and which makes their flesh taste exceptionally sweet.

As a result, in recent years, it's made Kep a bit of a go-to foodie destination in Cambodia; people come here from miles around (even from the capital, Phnom Pehn, three hours' drive away) to buy fresh seafood to cook themselves, dine out, or both, while the crabs are also exported to the US and Europe.

As the morning progresses, the fishermen, who have been doing this for generations, wade through the water to open the traps. Inside are writhing, wriggling masses of crustaceans, with their distinctive, electric blue-coloured legs and claws, blue-and-grey speckled backs, and toothpaste-white bellies. Once their claws have been secured with elastic bands, they'll be stored in baskets in the water to keep them fresh until they're sold.

For as long as people can remember there's been an abundance of crab here 

Market Price

Kep's market opens around 6am, when hungry housewives, local restaurateurs and crab shack owners head to the beach to start haggling for the wares. Here is where the division of labour starts: selling is done largely by women, dressed in distinctive, floppy-brimmed hats with neck-scarves attached to shield them from the fierce sun.

By eight o'clock, the seafront is thronged with voluble people, gesticulating wildly, some shouting out prices, some shrieking 't'lay na!' ('too expensive!'), examining the goods – female crabs have roe inside them, but male crabs have meatier claws – and filling up baskets.

The price varies depending on the size; small ones go for around $6 a kilo, bigger ones for $9 a kilo. Periodically, the fishermen bring over huge nets of yet more crabs, which are poured out into plastic containers, their shells clacking rhythmically like falling dominoes as they cascade on top of each other.

I'm gazing in awe at the whole scene, which can best be described as organised chaos. The crabs are the mainstay of this relatively compact market, but it sells almost everything else, from stinky durian fruit to underwear and kitchen equipment.

My effusive local guide, Sarath, explains that 30% of Kep's population of around 28,000 people are fishermen. "They set traps for the crabs during the day," he explains, "and at night they go in search of squid, shrimps, and other fish." Some stall-holders sit in front of big buckets of live seafood, while others man charcoal grills where you can buy skewers of prawns, snapper, stingray – even shark.

Many locals will take their purchases to one of several women who'll kill and cook them on the spot. I try not to wince as I glimpse one, hard at work, calmly driving a metal spike through a crab's central nervous system, before handing it over to a colleague, who plunges it into a vat of boiling water for 15 minutes.

Groups of families are picnicking nearby, devouring the freshly cooked flesh with rice and chilli sauce – for breakfast. Well, that's one way to start the day… I wimp out and instead stuff my face with a spicy, deep-fried fish pancake, followed by grilled banana and sticky rice, wrapped in a palm leaf.

Five more crab shacks in Kep

Maelis

Bag a table facing the water (like many of these restaurants, it's built on stilts, right over in the sea) and order the fried squid with kampot pepper or fish amok.

Diamond Jasmine

A friendly, family owned business, whose highlights include curry crab, and prawns with kampot pepper.

Holy Crab

Slightly more upmarket than many of the other restaurants – and with prices to match. I recommend the crab soup with mushroom.

La Baraka

A bit of a Kep institution, this also sells western dishes (like burgers and pizza) but don't miss the steamed crab amok, which comes with a creamy, coconutty sauce.

Chau Chau

A solid and reliable venue turning out the local mainstay of crab with kampot pepper, as well as other dishes like fried squid with lemongrass and curry prawns.

Spice of Life

Kep is an unassuming, chilled little place on the southernmost tip of Cambodia. There's not much to do here, apart from swim, sunbathe, or eat, unless you can rouse yourself to visit the beautiful National Park, with its forested hiking and biking trails, or take a short boat trip to nearby Rabbit Island, a peaceful, sandy little enclave scattered with several bungalows and a couple of eateries.

It became a favourite weekend resort of the colonial French in the early 1900s, who named it Kep-sur-Mer and built themselves some rather fabulous beachfront mansions, which were then appropriated by wealthy Cambodians after the French left in 1953.

Today they lie in ruins, after their destruction in the 1970s by the Khmer Rouge. The rural drive here from Phnom Penh takes us past lush, green rice fields, populated by the odd lumbering water buffalo and wide, flat salt pans (salt production is a big industry here). Random cows periodically wander into the road – "we call them Cambodian tractors!" laughs Sarath, as they're used for ploughing.

Kep's main feature is its mile-long, curving, sandy beach, lined with the prerequisite palm trees. Behind it, in a line on a street known as The Strip, sit a range of informal crab shacks, bars and restaurants, all of which vie, with different degrees of friendly aggression, for your business. Each one has the town's signature dish, fried blue crab with green kampot pepper, on their menu, though some do it better than others.

I attack the claws with metal crackers, easing the sweet, delicious flesh out onto the plate

On my first night, I head for a drink at The Democrat, amusingly decorated with pictures of all the US Democratic presidents. I order crabcakes with my beer; for $5, I get a plate of three large ones, the meat fleshy and substantial, not padded out with any other ingredients.

Next door is Kimly, which also sells prized mud crabs, which are rarer, and caught in the local river. But, after chowing down on some fresh summer rolls and grilled chilli squid, I go for the main event. The blue crab arrives partially dismantled, but I still have to attack the claws with metal crackers, easing the sweet, delicious flesh out onto the plate. The peppercorn sauce is a tangy contrast; I bite into a whole corn, which is intense and full of mild fire.

The next day Sarath takes me to one of the nearby peppercorn plantations, to see how kampot pepper grows.

Kampot is a bigger, busier, backpackers' town, just 20 miles from Kep, and Sothy's sustainably run, eco-certified pepper farm lies between the two.

It's only been revived relatively recently, as many of these farms were also abandoned during the Khmer Rouge years. Pepper vines grow up poles, explains the farm's genial owner Sothy, on the rich, quartz-infused red soil of the elevated land. After three years, the peppercorns are harvested between March and May, when they have turned red, and have a mild and sweet flavour.

Getting there

Getting there

Cathay Pacific flies to Phnom Penh via Hong Kong from around £466 return (cathaypacific.com). Buses go from Phmom Penh to Kep from approximately $4 one way (visit tourismcambodia.com for details).

ABOUTAsia Travel (aboutasiatravel.com) offers high-quality tailor-made packages to Cambodia, Laos, and Vietnam, including expert guides, private transfers, and accommodation.

Farms like this produce several different types: black pepper, which is when the red peppercorns are dried in the sun for several days; white pepper, which is when the red peppercorns are boiled until their outer husk falls off, and which has the strongest flavour; and green pepper, which are unripe peppercorns, generally used within a week of being picked.

Kampot pepper is considered to be among the finest in the world, and has been awarded Protected Geographical Indication status, the equivalent of DOC (for goods like champagne or parma ham). About 70% of it is exported, mainly to Europe.

Later on, I stroll back along the seafront at dusk. I pass the huge 'Welcome to Kep' statue of a blue crab waving one of its claws jauntily at visitors and passers-by and a profusion of small beach huts to reach the white sculpture of a woman looking out to sea, apparently waiting for her wandering husband to return to her.

In the distance, more boats line the horizon, the silhouettes of their crew standing out against the setting sun. Tomorrow will bring yet more of these crustaceans; and they're definitely worth getting up early for.