I could feel bubbles of panic on the edges of my mind but I forced myself to concentrate on my breaststroke. Arms parting, arms parting. Focus. 

I knew if I started worrying about hypothermia, exhaustion or the cramping in my right leg, panic would cause me to shake or flail. 

Focus. Focus.

Ten years ago, I began a practice of swimming in Humboldt Bay. Humboldt Baykeeper, the nonprofit that monitors the health of our waters, had assured me it was clean enough to swim in. After all, the bay hosts the largest oyster crop in California, along with seals and sea lions. So I stopped driving to Arcata to swim, bought a shorty wetsuit and booties, and started clambering off the C Street dock into the water several mornings a week.

A few months later, I heard about a group of swimmers who drove to Stone Lagoon to swim on Wednesdays. One chilly, gray March morning, I met three other women, all strangers to me, at Wildberries to carpool.

At the lagoon, we stood at the edge of the boat ramp looking out. All I could see was water and a few vague, far-off shapes in the mist. I remember one of the women, a competitive triathlete, saying with a slight shudder, "It's always bracing!" Then we were off.

Well, they were off. Within 30 seconds, I could barely glimpse them through the thick fog. I followed — or thought I followed. "I'll see them on their return and swim back with them," I thought.

It seemed a long way to the other side. I didn't know Stone Lagoon back then, having never swum or paddled in it before. I had stopped at the parking area driving back from Crescent City but barely looked at the water.

I kept going and going until I started seeing bits of vegetation emerge in the mist, and finally touched ground at what I assumed was the far shore. I paused and took stock. Would I be better off returning by hugging the shoreline? I guessed that would take a lot longer. No, better to go back the way I came — surely I'd run into the others somewhere en route.

I began swimming back. Somewhere in the middle of what seemed a vast body of water, I started to feel very small and very alone. Looking left, I saw water but no shoreline. Looking right, fog. Straight ahead, fog. I tried calling loudly a few times. "Hello," I shouted. "Anyone there? ... Hello?" Nothing.

"Just keep going," I told myself. Arms parting, arms parting. My mantra. Don't think of anything else. Focus.

As I slowly neared the shore, the fog thinned and I could make out what looked like thicket. It still seemed far and it was taking a lot of time. I wanted to get there so badly. Finally I tested with my foot and felt the relief of squishy ground. I could stand.

But there was no boat ramp. Where was I? My hunch told me to head south, so I swam and crawled in that direction, and in about 10 minutes glimpsed the vague outline of a structure, and then, minutes later, the ramp.

Two of the women were standing there, one in her wetsuit, about to head out to look for me. "We were so worried," said the driver. They had been waiting about 25 minutes. The third woman had hitchhiked back into town in order to make jury duty.

As we drove back, I sat in the passenger seat trying to warm up while the driver talked. I listened, fighting tears and still shivering after the adrenaline rush, the fear I could not let myself feel while swimming, now teeming out of every cell in my body. "Uh huh. Uh huh," I repeated, not wanting to break down in front of these strangers. It wasn't the first time I responded that way in a traumatic situation — I simply act with decisiveness and focus. It's only after the danger has passed that feelings surface and pour out, uncontained.

Perversely, in retrospect, my main reaction in the car was embarrassment at getting lost, holding everyone up and forcing the other woman to hitchhike into town. I avoided turning my head and making eye contact with the woman seated in the back, staring instead at the Patrick's Point and Trinidad exits as though they were objects of great fascination.

In Arcata, I had an appointment to meet with a colleague. Looking back, having kept the date is one of the most surreal aspects of that whole bizarre morning. During the half-hour wait before our meeting, I wandered around the aisles at Wildberries, disoriented and spacey. Now I wonder why I didn't cancel the meeting after I called my husband, who urged me to come home.

When I did get back, he was furious, as was my sister, a former lifeguard and swimming instructor, when I called her. "How could they abandon you?" they both asked.

A flurry of emails followed from the driver, the only one I ever heard from. "I really hope the foggy experience didn't turn you off of lagoon swimming! Please accept my apologies for not being more vigilant about your first swim with us. I should have given you more direction, particularly because of the fog." She was very kind.

"Oh, I will come back and swim again!" I emailed back cheerily.

But I never did. I have never seen any of those swimmers since.

Now, 10 years later, I love paddling on my stand up paddle board in Stone Lagoon, the contours of which I've since become familiar with. But every time I'm on the lagoon, even if I'm laughing as the ducks play, a moment arrives when I suddenly remember the chilly, misty day I felt utterly alone, and I shiver all over again.

Safety Tips

I made several potentially hazardous errors on my first lagoon swim but I did instinctively follow the first and arguably most important safety rule:

Stay calm.

Always swim with a partner.

Know your surroundings. If you don't know the area, swim along the shore only.

Check the weather conditions before you go.

Wear a wetsuit and other appropriate swim gear to avoid hypothermia.

Carry a waterproof whistle.

Louisa Rogers still loves water, but these days she prefers to be on it rather than in it. She prefers she/her pronouns.