I see her as I step out from among the sea grape trees and onto the golden sands: tanned, blond, and bikini-clad, she is walking toward me. And she possesses the one thing I'm yearning to see in a woman on the beach: a little kid.

I'm in Rincon, on the west coast of Puerto Rico, with my 3-year-old son, Kai - just the two of us, for six days - and my best hope for doing anything besides parenting lies in other people's children. If I can find playmates for Kai, I might sneak in a surf session, a jog, or some uninterrupted reading.

After a three-hour drive from San Juan, we pull into Rincon, which tumbles from a blunt, hilly peninsula into the sea. The town's beaches are renowned for surfing, although those on the sheltered southern side of the peninsula are often glassily calm.

Along one crooked road we find our lodging, the Boarding House, a pleasant guesthouse in an otherwise residential neighborhood. It's also a surf school, with boards piled in the driveway. Before even finding our room, we ascend to the rooftop deck for a view of lush forest cascading to the sea, which looks to be a long walk away.

But we set out along a narrow road that ends at bikini-girl-and-her-son beach, known properly as Pools.

"This is Robert," the blonde says, patting her son's head. "We've met another family with a boy named Kai! He's 5."

Her name is Michelle, and she's from Ventura, Calif. Along with her boyfriend, Rob, 6-year-old Robert, and her friend Jessica, she's renting a stately pink house right on the beach. The cove is idyllic in appearance, but it isn't Rincon's best surf break, plus the rocky waters discourage kid swimming.

Then, as if reading a script from the vacation gods, Michelle says, "We've been taking turns surfing and watching the kids. If you want to join us, we usually head out around 9."

Kai and I walk across a street overhung with tropical vegetation and dine at a thatch-roofed cafe and hotel (also called Pools), where the portions are small but the rum punch is redemptive. The bonus is the adjacent swimming pool, which occupies Kai and a few other kids while I have my second uninterrupted adult conversation of the afternoon with an entrepreneur from San Juan and his wife. Not bad for Day 1.

I carry Kai most of the way back up the steep road to our guesthouse, but it's happy work. The yodels of coqui frogs ride on a dusk breeze, the smell of nectar drips from the trees, and my weary boy lays his head on my shoulder. We are both dead asleep by 7:30 p.m.

In the sparkling morning sunshine, we open the door to our efficiency to find a cat, possibly stray, which Kai immediately befriends. As I pack for our day - stegosaurus, triceratops, T. rex (and maybe sunscreen?) - boy pulls tail, cat bites boy, crying ensues, prompting soothing laced with genuine worry (bleeding wound!) and the eventual evaporation of 45 precious vacation minutes. All this, mind you, before coffee.

Next up is a strident campaign for a screening of Curious George II: Follow That Monkey on the iPad, which culminates in my buying the movie on iTunes so that we can take it mobile.

To really check out the town and beaches, we have to drive. We stop on Route 413 at the Banana Dang coffeehouse, a Rincon icon with a laid-back vibe. The coffee is wonderfully strong.

By the time we arrive at Pools beach, Michelle and crew are gone. But there's a Puerto Rican girl about Kai's age and her dad, who sits on a shaded rock making cellphone calls while the kids play around a tide pool. I unfurl a towel and a New Yorker magazine and settle in.

I decide that this will be a Kai day, a wise move given that Kai had long since decided the same thing. For lunch we drive up the hill to the El Batey grill, an outdoor counter where chef Carla grills a juicy chicken kebab as we gaze down to the white-capped sea and the rocky silhouette of Desecheo, an uninhabited island 13 miles offshore.

We drive south through bucolic fields that rise from the sea into forested hills. Unimpressed by the horses grazing, Kai asks whether real dinosaurs live here. When I shrug - who can say for sure? - he christens the fields Dino Land.

Smack in the middle of Dino Land, an unmarked dirt track brings us to the best father-son beach we will find.

We release a crocodile, a tiger, and a pachycephalosaurus into a sand pit, and eventually hit the water together - Kai hugging my head while I struggle to avoid drowning - before repairing to the lone on-site structure, a little lunch shack, where we chow down on empanadas.

Rincon is peppered with spots like this beach, natural beauty left largely natural, with a hint of a rough edge (theft from cars is a minor issue in many of the rutted dirt parking lots) and as far as I can tell, locals and visitors are happy to leave the luxury to more snooty Caribbean destinations.

On Day 4 we finally link up with the surfing families on Maria's Beach. It's a sweet setup: ample shade, room for the kids to play, surfboard rentals, and a bar/restaurant across the parking lot.

Shoulder-high rollers break over a reef about 100 yards offshore. The women are surfing and, after a few minutes of pleasantries, the other Kai's dad, Cameron, offers to watch the kids while I head out.

This is the pinnacle of my quest, and yet when it comes time to leave my child with someone I've known only a few hours, I hesitate. I amble over to the board rental guy. Yes, he says, totally safe break, perfect conditions today. Take a board. Pay when you return. No stress, man.

I walk back. My Kai ignores my questions - Food? Drink? Pee? OK if dad goes surfing? - so I shrug at Cameron, tell him to wave his arms like a maniac in case of emergency, and head out.

It's a solid session, and between the swells, I can see Cam from the distance, his non-flailing arms suggesting that all is well. When I return, my Kai hardly notices.

The next day, the other Kai and his family head home, and the swell fades. We run into Michelle, Jessica and the Roberts at the smooth-stone beach, but there's no pressure to take shifts: We hang out, share stories, dip into the calm sea and play with our kids.