In the end it was not the pod of orcas approaching her vessel that really scared Zara Lachlan as she rowed solo, unsupported across the Atlantic over the winter months, although they were “huge” and “frankly pretty terrifying”. Or the shark that trailed the 21-year old’s boat for 45 minutes after she cut her leg and bled into the sea. Or even the barracuda that “took a large bite” out of her foot as she dangled it over the side.

“The scariest moment was actually when I had a near-miss with a big ship one night,” says Lachlan. “It passed within 0.1 miles of me, which is really nothing in the ocean. It had no idea I was there. It hadn’t seen me on the AIS [the tracking system that alerts vessels to each other’s position]. That really could have been it. But that doesn’t sound as exciting as a shark.”

Lachlan, who last Saturday became the first woman, and youngest person, to row solo, unsupported and non-stop from mainland Europe to mainland South America, laughs. She certainly has some colourful stories to tell her university friends when she goes back to Loughborough to complete her physics degree over the coming weeks.

Truth be told, Lachlan – an Army reservist who will be heading to Sandhurst this autumn to train as a technical officer – is still kicking herself that she did not break the record outright for fastest crossing. Arriving into French Guiana 97 days, nine hours and 20 minutes after leaving the shores of Portugal on October 27, she was 19 hours slower than the only other person to have completed the voyage.

“I would much rather have missed out by three weeks than 19 hours,” she admits. “Because all I could do when I got into French Guiana was pick apart my last three months and think about the days where, you know, ‘Oh, what if I had done this differently?’ It was really difficult to have something be all-consuming for over three months of my life, and then not to achieve my goal. I struggled with that for a few days, but I feel a little bit more OK with it now.”

Lachlan, who was supported on her challenge by Team Forces, an Army charity, was actually aiming for 60 days but endured horrific luck with trade winds, which did not play ball at all. On some days she would row for “21 or 22 hours essentially to stand still”. Lachlan would then deploy her “sea anchor” – a large parachute which hangs off the bow of the boat to slow its drift – and grab a couple of hours’ kip knowing she would lose more ground while sleeping than she had gained rowing.

“For the first 39 days, the weather was against me for 35 of them,” she says. “They were hard, hard weeks. I had a log book and pretty much every single day in the Canaries I just wrote ‘soul-destroying’, because it really was.”

Lachlan is clearly made of stern stuff, though. Having signed up for the Army at the age of 15 (she started rowing at Welbeck, the Army’s sixth-form college), she is not the sort to be deterred by unhelpful trade winds, flying fish (one hit her in the face), orcas or sharks.

Even after she broke her phone, and with it her source of music, and began to hallucinate, she ground it out. “I actually had a great time hallucinating,” she says. “All of my hallucinations were really pleasant. Lots of grey horses running towards me when waves broke. And I had birds swarm the boat one time and they turned into flowers and then just disappeared, stuff like that.”

Lachlan called her boyfriend at midday every day on her satellite phone so that she did not go completely mad. “I’d say it kept me sane, but I’m sure he would say that he just watched me get madder and madder,” she observes. But other than that, she was all alone.

Apart from the container ship in the night, the nearest she came to disaster was when she got into the sea one day to clean her boat and forgot to lock off her rudder. A big wave came along, the boat’s auto-pilot kicked in, trying to keep the boat straight, and she was thrown towards the moving rudder.

“I hit my head really hard,” she recalls. “And I just started drinking water because I was so disorientated. I managed to clamber back on to the boat and just lay there for a while waiting for my senses to come back.

“Again, that was a lot more dangerous than a shark following me, behaving all nicely, or a barracuda taking a bite out of my foot. With the barracuda, I was actually more worried about getting an infection than getting eaten, because they’ve got so many bugs in their mouth.”

Lachlan made it in the end, showing huge grit and determination, and raising money for two charities, Team Forces and Women In Sport, in the process. For a 5ft 8in, 64kg (10st 1lb), 21-year-old who was “not a great swimmer” and “dreaded getting into the sea when I set off”, it was no mean feat.

So, any chance of going again to knock off that record? Lachlan laughs. “Umm, I’m not sure what my boyfriend would say about that. But I definitely want to do something else. Even at the hardest points of this trip, I still felt lucky to be there. It was an incredible experience. And I do want a world record.”