Hue is definitely the most Francophile city we’ve seen in Vietnam, but it also shares one charming characteristic with Manchester – it sees a higher annual rainfall than anywhere else in the country. So after a laid back few days there, with a dodgy weather forecast looming, we decided to head North across the demilitarised zone and into Northern Vietnam – first stop, Dong Hoi, the best place to visit the Phong Nha Caves from.

Dong Hoi is a fairly innocuous little town but we very nearly fell out with it within an hour of arriving due to the difficulty of finding a place to stay: thanks to a friendly Vietnamese law, some hotels are not permitted to allow foreigners and apparently this is the case with 90% of the establishments Dong Hoi – everywhere we asked, bashful shrugging and half-hearted head shaking was the standard response. We traipsed around for an hour feeling like social pariahs until we finally found a place that would take whiteys and collapsed into bed, crossing our fingers that getting to the caves the following day would not be quite such a battle.

No such luck. The only place that would arrange transport was the governemnt tourist office (looked like a nineteen-seventies accountancy firm, staff about as cheerful as Myra Hindley), where we were asked for an insane amount of money to get us there, so we politely declined and began to trawl the streets again in search of a cheaper option. Thankfully, we were rescued by Nam, the cheerful owner of a little coffee shop, who called his mate and persuaded him to drive us there for a much smaller fee.

The Phong Nha caves themselves are the largest cave complex in Asia – 35km of underground caverns and tunnels formed over 400 million years – the first 8km were used as a civilian shelter during the war but the rest of the tunnels weren’t discovered until the nineties when a team of British spelunkers stumbled into them. They are also one of Vietnam’s prime domestic tourist attractions – we didn’t know this until we got to the boat jetty (the caves are only accessible by river) and saw the Armada of little wooden boats settig off down the river, packed to the rafters with raucous families. We paid our entrance fee and joined the melee, much to the delight of the crowd, who were possibly more excited about the presence of four confused foreigners than they were seeing about Asia’s most spectacular cave system.

Despite the happy chaos of people and boats, the caves themselves are awe-inspiring – vast, echoing chambers linked by shadowy underwater canals, tunneling deep into the limestone cliffs. Some areas are lit by phosphorescent spotlights, making the stalagmites look almost ethereal, others are left gloomy and mysterious, looming over the water so that the boats look pathetically small. One we were inside we were able to disembark and wander round the main chamber, feeling like a speck of grit caught in an ancient, immovable old beast, before (rather gratefully) returning to the outside world and heading back to the jetty for lunch.

When we returned from the caves, Nam had booked us onward bus tickets and he even plied us with beer until it arrived. As we drank he explained to us how happy he was to be able to practice speaking English – he ran the cafe seven days a week with his wife and also spent three nights per week at night school learning foreign languages – he wants to visit his brother, who’s a taxi driver in the UK. This seems to be common with all Vietnamese people – they have an incredible capacity to work ridiculously hard and remain very cheerful. I must remember this next time I wincee at the thought of getting a job again.

At nine ‘o’ clock our night bus rumbled up and we stumbled on, headed for Ninh Binh, where we were unceremoniously dumped at four am. This is our base for the next few days while we go and visit some monkeys at an endangered primate rescue centre…hopefully they’ll be a bit friendlier than the last primate I met.