Finlay Wild is a top UK hill runner and mountaineer, having won many of the country's toughest races and set some impressive records on classic rounds and other hill challenges. This year he's been competing in the World Skyrunning 'Classic' Series - a competition taking in some of the most prestigious mountain races in Europe and beyond. From the first race in the Himalayan foothills, through the summer in Europe to the series finale in Limone, Italy he has been hoping to train smart, learn about these varied mountain places and cultures, and maybe even unlock some extra hidden running potential. Here he enjoys the party vibe of a Basque race like no other.

A month after experiencing the breathless heights of my first skyrace in China, I'm standing on the start line of one of the most iconic races of the series in the Basque Country of northern Spain: Zegama. Or Zegama-Aizkorri Mendi Maratoia to give its full name. I say standing, but in fact I feel more like a fan packed into a massive music gig than a runner waiting to start a race - I can barely move in the tight confines between the rows crammed in around me.

It's the most intense start I've ever experienced, the crowd is huge and going wild. Depa, a Basque legend sporting a powerful mullet and an inconspicuous cowboy hat is going mental on the loudspeaker, getting the crowd riled up. "Zegama!" he screams, dashing about in front of the five hundred amped runners and the countless spectators. He's going berserk and the crowd responds in kind. The epic hero music escalates and we're into full volume Chariots of Fire hedonism as every single runner is crazily fired up. Booooommm! Boom Boom!, the bass reverberates. And then the two minute countdown starts and things go up another notch!

The actual start is chaos - pushed from behind with hands on the man in front's back, we break out onto a short lap around the small village church. It's tight cornering at a crazy pace in a huge pack. A guy ahead falls and I have a split second to jump him. In less than three minutes we have rounded the church and the leaders are sprinting up a steep hill out of town. Already Zegama has delivered an atmosphere like no other.

"Zegama is Zegama" those in the know smile wisely, but for the rest of us it's an exciting mystery yet to be experienced. Every European mountain runner wants a place. Hands down it has the deepest field of tough competition that I've ever faced.

The race now covers around 7km of undulating forestry track at a speedy pace before descending to the first road crossing.

But first I want to take a moment to explain a little more about what makes this race so special. Less than an hour from the Atlantic coast, the tiny agricultural town of Zegama is, for most of the year, a sleepy relaxed place in the lush foothills of the Pyrenees. Nearby Aizkorri is an impressive limestone ridge of a mountain, although at 1551m elevation it is not a major Alpine peak by any means. Yet this race is famous, and every year competition is stiff. "Zegama is Zegama" those in the know smile wisely, but for the rest of us it's an exciting mystery yet to be experienced. Getting an entry can be difficult given that every European mountain runner wants a place. Hands down it has the deepest field of tough competition that I've ever faced. To put it in perspective, I (just) made it into the race preview of 23 hopefuls but was far from certain that I could even finish in the top thirty.

The route itself is very fast - mostly undulating singletrack with three main climbs and descents over marathon distance, with 2736m of ascent. Precisely because of the depth of talent here the pace is blistering throughout. It's less a question of pacing yourself as setting a breakneck speed from the off and gritting your teeth to make sure the wheels don't come off too early.

Running out of the mist the roar of the crowd builds and keeps on building until you turn the corner and come face on to the glorious din

Added to this already pretty exciting mix is the factor that makes the race so special and unique: the crowds. Around 10,000 spectators line the race course every year, giving Zegama its reputation as the Tour de France of sky running. The majority of the crowds gather at a few key points in the race, the busiest point being the climb from the Sancti Spiritu church to the rocky Aizkorri summit. It's hard to describe how this support affects you psychologically - I'd been told about it of course, but certainly underestimated its effect until I was in the thick of it…

From over a kilometre away I first heard the noise of the crowds as I descended through San Adrian's cave, perhaps a third of the way through my race and working hard against tight legs and the fast pace:

Running out of the mist the roar of the crowd builds and keeps on building until you turn the corner and come face on to the glorious din. Push on up the famous hill, the sheer noise and energy of the thousands spurring you on, deafening you. Feeling like a warrior going into battle; a sweat-soaked, muddy, bloody hero. Endorphin levels go through the roof; absolutely euphoric, sublime, analeptic…

"Venga! Venga!", "Up, Upa!", "Animo!" - I'd felt a bit sluggish in the first half of the race but all this adrenaline gave me a strong second wind and I felt good. The only real technical section of rock hopping along the high ridge from Aizkorri went by in an enjoyable haze as I started to overtake others. Descending, I placed a foot wrong and felt a pull and pain at my ankle. Thankfully it was only a minor strain and I ran on without it hindering me.

Approaching the final climb there was yet another huge crowd. Even though the very lead runners were already past, the support was loud and sincere. At this point I knew there were 'only' 8km of undulating mostly downhill trail to go. This part particularly is known for a substance you wouldn't particularly associate with Spanish running - mud! Yet this region of Spain has a very wet climate and the lower parts of the route can get very muddy. Race day was dry but the preceding week was full of heavy thunderstorms. The ground was surely well prepared for a Scottish runner?

Thick in the forest there was nothing to do but follow the muddy leafy tracks and keep pushing. I was glad to have prior knowledge of this section as at least I knew roughly how far I still had to go. After a series of winding turns and several small uphills that felt much bigger than they should have, we finally reached the steep downhill road section which leads the final kilometre back into town. Position-wise I knew I was a bit back, but not exactly how far. This didn't particularly seem to matter though as I had loved the race, for all the other reasons, and also knew I had run fairly solidly besides. Right now though I had a problem - I had just been overtaken...

The language barrier it turned out was not a barrier to kindness, and we were ushered confusedly into various smiling rowdy social club rooms. Being plied with local cider and cake was a great way to recover

Having raced hard for four hours I didn't feel like conceding even one place easily now. A sudden surge of energy, competitive spirit or just stubborn determination hit me - another synaptic stimulation on top of the adrenaline from the crowds, and the caffeine gels I'd been slurping for the past few aid stations. A full out downhill tarmac sprint battled ensued, reminding me of a previous horrible experience years ago rattling down the final hill into Llanberis on the Snowdon race in thirty degree heat, desperately hanging onto a disappointing tenth place.

This felt more positive though and as I eased back ahead we careered down the final steps into town. The crowd were mental again and their energy pulled the runners along the final straight. Still on a high from my sprint I finished fast and just a second outside the top twenty. The music was still booming, the crowd still large, and Depa still stomped around the finish area shouting into the mic in Basque. Although in terms of position this was my worst result pretty much since I started racing, in terms of experience I absolutely loved the race and its teeming cheering crowds. I'll definitely be back, and perhaps with this experience under my belt and having gained a few ideas for improvement I can surely whittle my time down a bit.

But for now it was time to rest. Well, rest briefly and then party! As you can image for such a well-supported race, it also has a reputation for a well attended afterparty. To explain this, I first need to give some background on the levels of hospitality we experienced from the locals. I had been one of the first few racers to arrive in town, and as a result was already getting nods of recognition from passing locals. But Ryan the Kiwi had arrived first and was met with very special hospitality: he was taken in by a local family and not only given his own room and board but also taken out to all the local watering holes and attractions in the week before the race, and pretty much given the freedom of the village. The language barrier it turned out was not a barrier to kindness, and we were ushered confusedly into various smiling rowdy social club rooms. Being plied with local cider and cake was a pretty great way to recover, and later in the pub we were instructed in the Basque game of pelote - squash without the rackets - but proved inept at it when an impromptu game broke out against the nearby church wall.

The next day some of us were roused and recruited to visit the local primary school. Questions were read out in Basque, Spanish and English and we were interrogated about our favourite parts of the race; what was the furthest, hardest and highest running we had ever done; and why we felt Zegama was such a special place. Witnessing the locals kids' involvement with the excitement of the race yet again brought home how much it means to the local community, something I've seen in many countries but probably never before in such a big way. The kids didn't seem to mind that none of us had been amongst the winning runners, as we signed a hundred exercise books in a long procession. And the hospitality continued back in the staffroom too as the teachers opened another bottle of local cider at eleven am. Well, it would be rude not to...

• Finlay is supported by Mountain Equipment and Norman Walsh Footwear