The problems begin when Brancão, our dreadlocked surf instructor, runs out of limes. We're gathered on the terrace at our guesthouse, or pousada, for a barbecue to celebrate the end of our week on the waves. The choice at Brancão's makeshift bar is simple: chilled cans of Skol, Brazil's default beer, or caipirinhas – the ubiquitous and dangerously quaffable national cocktail.
Most plump for the caipirinhas and all's well as Brancão crushes chopped limes and ice, adding generous slugs of cachaça (distilled sugar cane juice). But when we exhaust the fruit supply, Laina, a sassy New Yorker, doesn't want beer. So, watched with incredulity by the few sober members of the group, she retrieves used limes from empty glasses in an attempt to extract more juice.
She fails and, with only ice to dilute the cachaça, Laina's caiprinhas, we declare between gulps, are eye-squintingly awful.
There is a mild look of fear in our bloodshot eyes the next morning. The barbecue marked the last night, but we still have one more session of surfing. What's more, for the beginners among us today's the day we go to "the outside", the feared stretch of ocean where the big waves rear up like spitting monsters and crash down, hurtling towards the beach as gurgling humps of supercharged water. An early night under our ceiling fans would have been better preparation.
We arrive at Engenhoca beach near Itacaré in the Brazilian state of Bahia, to find the outside looking, well, huge. A full moon and far-off storms create powerful tides and violent waves. After warming up in the chest-deep "inside", where waves lose height as they near land, I join Brancão and Oscar, a Dutch trader, at the far end of the beach.
First we must tackle "the channel", a stretch of water hugging jagged rocks where, in theory at least, the waves don't break as big. Lying on our boards, we paddle out like two hatchlings behind Brancão's mother duck.
"Turtle dive," Brancão shouts as a metre-high wave breaks in front of us. A turtle dive is a long boarder's way (beginners get big, buoyant boards) to slip under waves. You capsize and then grip the edges, or rails, as the water passes overhead before flipping back over.
"Aah, adrenalin!" Brancão shouts over the din after we get the spin cycle treatment for a sixth time. And then peace. We've made it to the outside having paddled more than 100 metres. Catching our breath as we straddle our boards, bobbing in the swell, the sun is low over the beach, illuminating the frothy crests of the giant waves crashing back towards the shore. The sound goes with the waves and there is an eerie quiet.
"Simon. Come." Brancão paddles towards the break and I follow, my heart pounding against my board. After a few metres he stops and scans the Atlantic, looking for the next set of waves. We don't wait long. "OK, turn your board!" I see a huge wave beginning to break.
"No! No! No!" Brancão shouts. "Go! Go! Go!" is what I hear above the roar. I paddle like crazy to catch the wave. It lifts me up, tips my nose down, and swallows me whole. I squeeze my eyes shut and try to relax my limbs, as instructed.
I perform a submarine cartwheel before I feel a violent tug on my ankle as my board gets hauled towards the beach. Some seconds later I surface. "I say 'no', why you go?" Brancão yells, before the next wave drags me down. Now closer to the beach, I ride a small wave back to land, and sit, feeling dazed but utterly alive. Surfing, I decide as I start psyching myself up for another go, might just be the world's most effective hangover cure.
Five days earlier I had arrived in Itacaré, a scruffy but charming fishing and surfing town on Bahia's "Cacao Coast", a stretch of rainforest and beaches two hours' flight north of Rio. The town promises warm waters, reliable conditions and beginner-friendly breaks – ideal for surf virgins such as me. I'd signed up for a week-long surf camp – perfect, I decided, for people who like beaches but not enough simply to sit on them.
Day one starts for beginners (I'm joined by Oscar and Emma and Amy, two young Brits) with a theory lesson at surf school HQ, a beautiful bar and restaurant where students meet every evening for a video debrief (every wave is filmed) and a drink. Then, furnished with longboards and leashes (to keep the boards close in a wipeout) we head to the calm waters of Concha, the town's main and only waveless beach.
"One, two, three!" has become a mantra by the end of the morning. Advanced surfers hop on to their boards but beginners learn a three-stage routine, which we must practise on the sand over and over again. "This is like a bootcamp," remarks Emma as our thighs, unused to adopting the surfer's stance (legs bent, head up, knees pointing inwards), feel the burn.
Staying upright at all is a challenge on day two – our first visit to Engenhoca. Surfing, it turns out, is seriously exhausting. Just catching small waves involves walking out through them which, with the strong incoming tide, is like wading through treacle. After receiving a dozen body blows from waves, we have to turn our dining table-sized boards, lie on them and paddle to get speed. Then you have to remember the 1,2,3. Invariably I fail and have to make the "treacle trek" countless times. But perseverance pays off and I manage to stand up, albeit with the poise of a greyhound on a tightrope.
A tour of a nearby rainforest the next morning is a hit. We're shown round by Claudio, who was a L'Oréal sales manager in a previous life. He now works to preserve and show off one of the last tracts of primary forest on the Bahian coast, home to a record number of tree species (more than 400 at the last count).
Some of them are more than 800 years old and Claudio's passion for his new habitat is infectious.
That evening we catch up with the rest of the group, which includes an Israeli, three Brazilians and a German, all of whom are also travelling alone. Firm friends after three days, we start the evening routine with a stroll along Rua Pedro Longo, the cobbled main street and home to surf shops, restaurants and bars. After dinner at the Kilo, a cheap buffet where the weight of your plate determines your bill, we drink caipirinhas at Favela, a shabby outdoor bar. Then it's to Papagaio, an outdoor dance hall where hip-swaying young locals dance the Forró, north-eastern Brazil's answer to the Samba.
Back on Engenhoca on the final day, time's running out if I want to catch a big wave. I've stocked up on tapioca pancakes and cocada, a sweet made with grated coconut (Itacaré's answer to energy food ) before heading back to the outside.
This time Brancão watches from the beach but, as a set sweeps in, there's no time to feel lonely. This is it. I paddle hard and for a moment think I've missed it but a few more strokes keep me on the crest and suddenly I'm gripping my rails with white knuckles as I'm consumed by foaming water.
After a second I emerge in front of the maelstrom, my board juddering as it's whisked along. Then it's time to stand up. It's not pretty but I make it. The wind is in my hair, the setting sun is in my eyes and I'm riding a metre-high wave towards one of the most beautiful beaches in Brazil. That's worth another caipirinha. Just make sure the limes are fresh.
Travel essentials: Brazil
The writer travelled with Access Trips (001 650 492 4778; accesstrips.com), which offers an eight-day surf camp in partnership with Easydrop surf school (00 55 73 3251 3065; easydrop.com) for US$1,024 (£683), excluding flights. The cost includes B&B, six surf sessions and transfers from Ilhéus airport.
Brazil Tourist Office: 020-7399 9000; brazil.org.uk