Snorkeling and fishing off Carmen Island. It’s the Sea of Cortez, but it feels like the Fountain of Youth to a 74-year-old on an island-hopping tour that includes kayaking, snorkeling and camping (Mary Harter)

As I bump my way gingerly — and a bit fearfully — up the ladder of a boat bobbing in deep water, I resign myself to the inevitable black-and-blue marks that I know will result. Bruises, like wrinkles, pop up anywhere at any time on thinning skin.

I am on a sea safari in the Sea of Cortez (a.k.a. the Gulf of California), off Mexico’s Baja California coast, a kayaking-snorkeling-camping expedition that I’ve undertaken with some trepidation. I’ve never been kayaking before, and I can’t honestly say that I love sleeping on the ground in a tent in “Survivor” mode. But as a woman of a certain age, I’ve come to believe in seizing the opportunity for adventure before all notion of adventure is lost along with the ability to pursue it.

I’m 74, yet on most days, I feel more like 40 (even if I don’t always perform like a 40-year-old). I do Pilates, swim, hike — almost anything to ignore, or rather undercut, the age factor. Still, though I’ve walked the heights of Nepal and lived for a time in Afghanistan, there are plenty of adventures I would never consider undertaking.

Play to your strengths, I say. I’m a decent swimmer, and I love the water. Kayaking, I assure myself, is one sport with both a soothing, placid side and a testosterone-tinged element for thrill seekers. Under the right conditions, that is. Conditions in the Sea of Cortez can be notoriously rough, depending largely on the wind. El Norte, sweeping down from the north, is not to be fooled with. It will influence our daily schedule, we’re told.

We are four supposedly hardy outdoor aficionados, strangers before we meet up the first day in La Paz, on the east coast of Baja California Sur, for what Sea & Adventure Tours (Mar Y Aventuras) calls its Island Hopping trip: nine days, with six nights of camping on a variety of beaches, plus a few land-based escapades on our way to the town of Loreto, farther north. It’s a distance of 143 miles as the crow flies (we won’t be paddling all that way), with a crew of three and Carlos, a seasoned guide who claims that he sleeps better on a beach than in a bed.

The minimum age for the tour, according to the company’s Web site, is 8. No problem there! Medical waivers are not required, so who’s to know that I have a rabid head and chest cold as we embark?

I’m the oldest in the group, I quickly determine. (My travel mates politely refrain from inquiring about the exact number.) While I usually avoid making very much of age, I likewise recoil from the flimflam that one’s later years are necessarily joyful. My genes have been kind, and I’ve helped them along. But I also know that it’s a woman’s fate to be judged greatly by externals. Hence, perhaps, Carlos’s watchful eye, to be sure that I don’t hold the others back.

Stephen, in his early 60s, manages just fine. A scientist retired from the U.S. Geological Survey, he builds airplanes and flies them around the globe. He and his friend Valerie, 60, have been on the trip before and come well-equipped. Forty-five-year-old Jason, a public defender from Phoenix, has pursued challenging adventures all his life. I’m happy to be bow to his strong stern in the kayak.

Luckily, on this our second day out, the motorized skiff that carries our kayaks when we have to go long distances or pause for snorkeling is moored in reasonably gentle seas. We have come in the late morning to Los Islotes, a protected sea lion preserve that’s a rocky satellite of Espiritu Santo island, where we’ve spent our first — sleepless for me — night. Five more nights to go, if I can hold out.

Fins, mask and breathing tube in place, I jump over the side with as much bravado as I can muster. To show off my false confidence, I smile and flap my hands together flipper-fashion over my head for the benefit of the two ecotourism students traveling with us to make a TV documentary. Dozens of sleek, sly mammals are waiting out here to play with visitors. The cameras come out; the creatures zoom in close. “Back away if any bulls come toward you,” Carlos cautions.

As a skinny white lady, I feel less like a potential playmate than a tasty bit of meat for denizens of the deep. I splash around, but few of the sea lions seem interested in me. My extremities soon grow cold in spite of the temperate water, my feet sore from the hard rubber fins. Why didn’t I think to put on socks? Relief awaits at the top of the skiff’s ladder, but I need stronger arms — the kind that lift heavy suitcases into airplane economy bins. An alert crew member intervenes and hauls me upward like another duffel bag to be stowed.

Snorkeling has its limitations, too; my ill-fitting mask regularly fills up with water. So while the men all eagerly dive for clams that become prime hors d’oeuvres for our increasingly delectable evening meals, I often forgo swim time and underwater views in favor of lounging on the skiff. I read, sketch, nap and let my mind wander: the all-glorious escape from routine. There’s no shame in this, Carlos assures me. He recalls one group that spent their days carousing on board without ever lifting a paddle.

I quickly adapt to the boat’s rolling motion and become absorbed in the stark but hauntingly beautiful shoreline. Only a few fishing boats are around. In truth, we see far better in the kayak, eyeing the many birds and marine animals up close: cormorants, vultures, pelicans, gulls, osprey and at least one goat high up on the rugged hills. Dip, sweep, alternate sides, coordinate the action with my mate in the stern: nothing too difficult to learn. The trick to achieving a graceful glide is in the wrist. Islands and beaches follow one another in succession — San Jose, Puerto Gato, Los Angelitos, Carmen — each different and waiting to be explored. One luncheon site is a stone archway, another a tarp set up on a beach of fossilized bones and shells.

We are not pressed to hurry except when trying to make it across the water before El Norte finds us. We don’t try to set any record in the number of miles we cover. That will fall to the group that Carlos will lead the following week — an all-male expedition going south against prevailing winds. Ours is a more leisurely excursion, allowing for lessons in botany and marine biology. Unusual plants and sea creatures abound in these unspoiled waters: tropical whales, scorpion fish, giant sea turtles, schools of manta rays and dolphins. If some of the skiff sorties are bumpy interludes, we at least have Jesus, the able driver, crooning love songs in Spanish, with Jason and the students singing along.

Experience and agility count most in the morning and evening chores of setting up and dismantling a tent. The poles and widgets are designed for veteran campers; carrying bags on and off the skiff requires muscle. After a weak protest, I happily give in when someone offers a hand.

And just as I won’t dare lift a 150-pound kayak, I can’t quite overcome the fear — doubtless from some childhood trauma — of sitting entombed in the vessel’s waterproof protective skirt, the cover that snaps onto the sides to help keep a paddler stable and water out of the boat. Nor will I attempt the rollover — a training exercise on deftly righting the kayak should a wave capsize it. After earnest lessons in kayak management and protocol, Carlos relents. He pointedly looks the other way while I draw the skirt around me but fasten only a few of the snaps. Luckily, the seas are mostly calm; we’re not likely to be engulfed. And anyway, Carlos monitors each boat carefully. As it happens, the only “danger” comes from a spiny puffin fish that gets entangled in one of our fishing lines.

At dinner each evening, we shed day clothes for evening wear, gaze up at the spectacularly bright stars and tell stories. Out of modesty, I sometimes sleep in the same shapeless linen dress that I put on after washing off the salt and sand (makes it easier when trudging off to the toilet in the middle of the night). Our shower is a plastic bag of water hung on the side of the skiff and heated by the afternoon sun.

Three days out, I begin to yearn for some familiar comforts, such as a sturdy mattress instead of the narrow blow-up pad that serves as my bed. But our varied meals, with beer and margaritas to help fuel the camaraderie, largely make up for the discomfort.

Fortunately, the sun always shines and somehow the packaged ice stays frozen in the portable chests.

Fortunately, too, there are no mirrors. I forgot to pack one and have no wish to borrow. Vanity is on holiday. Ah, bliss. Similarly, cellphones and clocks are forgotten — phones won’t work most of the time anyway — as we succumb to the rhythm of the days.

The effect, upon arrival in Loreto our last evening, is a revelation. I find a strange face staring back at me in the motel’s bathroom mirror, eyebrows bleached white above crease lines left from the sun, hair a stiff messy tangle.

Overall, however, I sense a lovely glow, a Vitamin D uplift, and ageless memories regained.

Geracimos is a former newspaper reporter and a veteran traveler.