They say you should do one thing every day that scares you. I can safely say that on March 3 I more than fulfilled the day’s quota. Diving into frigid, shark-infested waters for the Escape from Alcatraz Triathlon was one of the most terrifying things I’ve ever done.

This is a race unlike any other and nothing can or will prepare you for race morning. Not even I knew how to calm my nerves as we set sail through foggy darkness towards the eerie looking Alcatraz Island.

Knowing the boat ride is a one-way ticket and your only way back is a 1.5-mile swim through water that’s barely 11C is more than enough to get your heart racing before the gun goes. With 15 minutes to go before the start, the pros were all gathered along the edge of the boat with a guardrail as high as my chest in front of us. “So, do they drop this railing when we start?” I turn to ask the girl next to me.

“Err, no, we have to climb over that then dive in.” Ah. OK. I have visions of me falling in before the race has even begun.

School trips to the Isle of Wight suddenly come flooding back to me where, on the ferry, teachers drummed into us: “You do not go near the railings and you DO NOT climb on them.”

Every logical, rational part of my brain is screaming at me: “You do not want to climb over those railings! Have you seen that water? And there are sharks in there!”

Yes, OK, I hear you, but this is a race and in less than four minutes I’m supposed to be swimming all out to that beach.

In a bid to silence the contrasting voices in my mind, I dare myself to look across to Alcatraz Island. That doesn’t help. Oooooh, it’s giving me the creeps… With barely any sunlight falling on it, it looks shadowy and menacing. I recall a visit there as a tourist two years ago which scared me silly back then.

I’m broken from this self-imposed pre-race torture by the race director’s voice: “Two minutes to start, pros!”

HELP! I look down at the water again. I look across the bay. And then “HOOOOONNNKKKK!” the starter’s klaxon sounds, just a few seconds after the two-minute warning. What?! What’s happening? We’re off!

I see a cluster of male pros dive in, followed swiftly by most of the women. Arghh! They’ve gone! I’ve got to go too. Oh. Help. Me. Arrrghhhhhh!

Phrawwwwwhhhhhhhhh!

I’m suddenly splashing about. I’m in! One side of my goggles has filled with water, but I can just about see from the other. The water is as cold as I knew it would be but I keep telling myself I’m a hardy Brit and it’s no colder than Wimbleball Lake for 70.3 UK. Yes, you’re Great and British, Lidbury. Keep swimming!

I’m in a pack with some other girls but the current, wind and waves are so brutal that one moment you can be swimming together, the next a huge wave hits and you are thrown apart like fish spewed from a fisherman’s net. I am gasping for air. I try to breathe to my right. I get a face full. I try my left. Oh joy. The same! I remind myself I’ve been a competitive swimmer since I was 10 and I have the skills to get me through this. Really? Yes.

Concentrating so intently on being able to breathe and not drink all of San Francisco Bay leaves little opportunity for sighting and sadly I pay the price. With less than a half-mile to go I realise the current has pushed me and another girl way too far to the right. I cannot see anyone else. I finally get a reference point on dry land and see I’ve swum off course. Let’s not worry too much about that at this stage. Let’s just get onto the beach. Land! I can see dry land!

With a little stagger, I make it to the next stage: being vertical. I’m not entirely sure what’s happened to my feet or hands but I can’t feel them. I remember my coach, Matt Dixon, telling me to run hard out of the water and keep my wetsuit zipped up in a bid to raise my core temperature.

With fingers like claws, I make a bad job of putting my helmet on, but am soon on the bike and am enjoying this 18-mile ride. The course is fast and technical with lots of climbs and descents that take you into Golden Gate Park. I pass a few girls, but am also passed by a couple of others, so I realise I have no idea where I am in this race. I concentrate instead on pushing the pace and trying to ride as hard as I can. As a 70.3 racer who’s used to a 56-mile ride, I only just feel like I’m getting my riding legs as we hit the final stages.

With a few miles to go there’s one last climb which rewards you at the top with a magnificent vista of Golden Gate Bridge. This is racing turned sightseeing!

As I come into T2 I soon discover I’m in 5th place after a 53-minute ride and feel good. The run is an eight-mile out-and-back course which includes trails, pavements, beach running and the infamous Sand Ladder (400 sand steps). The crowds lining the early miles are a lot of fun and by the time I hit the beach (just prior to mile 4) I’m grinning like a loon. Having passed a girl on the way out, I’m now in 4th place and just have to make sure I don’t blow up on the Sand Ladder. From mile 5 onwards it’s all downhill and I’m delighted to be running home with a top five finish at this prestigious first race of my season.

Having spent the majority of the 2 hours and 25 minutes of the race dreaming of hot chocolate and a scalding hot shower, I take great delight in doing both (not concurrently) within a few hours of finishing.

I’m pleased to report that I recovered well and am now back home in Santa Monica preparing for 70.3 Oceanside, near San Diego, on March 30. More from me after that!