FROM Cabo Catoche, at the apex of the Yucatan Peninsular in Mexico, to the mouth of the Rio Hondo, the frontier with Belize, white beaches and turquoise seas stretch for 150 miles, one of the world's most stupendous coastlines.
This is the Mexican state of Quintana Roo, the top half of its Caribbean seaboard bursting with tourists, the lower half wild and all but inaccessible, known to fishermen, smugglers and soldiers trying to catch the smugglers.
Travelling south towards the deserted seaboard, the hopeful explorer does not get far. After more than an hour of grinding down a potholed way a thick rope lies like a warning across the broken road.
According to the map the route reaches further but according to the man serving beer at Boco Paila it is merely a track. 'After now,' he shrugs.
'Maybe you can walk to Punta Allen, if you can walk good.
It's twenty kilometres. After that you take a boat.' At the upper end of the state - the tourist bulge - Cancun is said to have been chosen as the perfect resort by a computer and it looks like it. Less than 30 years ago it was a sandy, narrow island shaped like a figure 7, the ocean on one side a lagoon teeming with fish and birds on the other, with local fishermen not realising they were working in paradise.
Then came the cement mixers and people seeking work from every part of Mexico, a quarter of a million of them in the end, and now, for every mile of the ten-mile seafront there are seven showy hotels, each one painted more garishly than the next it seems. And more on the mainland.
Yet there are compensations for the glitz.
Squeezed between the buildings the odd Mayan ruin sits quietly (there is a temple beside the third green of the Robert Trent Jones-designed golf course) and no modern indulgence can diminish the ageless sunsets. You can go dancing, watch a stage show and get married (all in the same day).
The energetic can go on a jungle tour or dive to the lairs of vivid fish, join a high speed convoy of jet-ski riders, or watch turtles who could not care less what you do.
Two people can dangle together below a single parachute over the sea and, for the more educationally minded, there is a Museum of Tequila.
And, of course, there are dolphins, enigmatically smiling while they swim with anyone who turns up, although if you happen to be pregnant don't bother.
'They backed off a lady who didn't even know she was expecting,' said the young woman who looks after them. 'They would not go near her because they heard two heartbeats.' There is no escaping it, Cancun is a loud place; loud colours, loud rock music belting across the exquisite ocean, and Americans from Montana and Wisconsin, amiable though they are, who shout as a matter of conversation, coming as they do from places where neighbours are far apart and there is plenty of air to shout.
THE Mexicans love their own noise, their brass bands and everyday sunny excitement. Cancun is in no way Mexico, but fortunately Mexico is not too far away. On the mainland live the families of the Mexicans who came and built the resort and who have now settled in their own home-made town.
People from the big hotels sneak over there for the eating and vibrant native life.
Puerto Juares is there, a jumbled harbour where the fishing catches are landed and from where the ferries go out to the Isla Mujeres, which survives as a real place despite the endeavours of tourism.
It was almost with a sense of relief that we saw what a haphazard place Isla Mujeres was. You could take tours around the island but my wife, Diana, and I remained in the town and we were glad.
There had been a tropical downpour and the streets were steaming.
A lopsided hotel faced the planked jetty and cheerful men cleaned fish on the foreshore badgered by comically hopeful pelicans. …