Camping at Manresa State Beach, near Santa Cruz, provides an education in nature

Manresa Uplands, Calif.

As 10 eyes peered down into the dark opening, we felt our bravery quotient take a severe hit.

“Uh, I’m not going down there,” said one of the four teenage boys with me on this trip, which was designed to combine beach camping with a visit to a college campus.

Until now, the three-day trip had been all fun and games -- goofing around on the sand, doing crossword puzzles, telling stupid jokes.

But as we stared at the muddy steel ladder that descended into the mouth of Empire Cave on the outskirts of the heavily forested UC Santa Cruz campus, a sense of real adventure -- and panic -- took hold.

It was decision time.

Setting up camp

THE BASICS There are 64 tent-only sites at Manresa Uplands. Vehicles park away from the sites, so campers must haul gear from the temporary parking/ drop-off area. Reservations can be made at reserveamerica.com with fees of $27.50 per night. There are restrooms, wash basins and coin- operated showers on-site. Firewood can be purchased from the campground host.

DRIVE TIME Head north on U.S. 101 past Salinas, then go west 14 miles on California 129 toward Watsonville. Head north on California 1 about six miles and exit at Mar Monte Avenue. Turn left on Mar Monte, drive one mile and turn left at San Andreas Road. Drive two miles and turn right at Sand Dollar Drive.

After mulling the options, one of my sons broke the silence : “I’m going in.”

In true Musketeer form, we followed one by one until the five of us stood at the bottom staring up at the hole of natural light from which we had climbed down. Now what?

I had brought with us a crude drawing of the interior of the cave that I had found on the Internet and determined that the cavern meandered at least 200 feet. As we poked around looking for the proper direction, a feeling of uneasiness settled in among the troops.

But before any of us could admit that maybe we had gone about as far as we really wanted, fate intervened: Our lone flashlight flickered and then dimmed to a barely visible amber. So much for our Hardy Boys moment.

We climbed out of the marble cavern and trudged up the trail that snaked its way back to the university, where just an hour before we had been but another group of prospective Banana Slugs, being given the official campus tour by a sophomore originally from Sherman Oaks.

Wearing an extra layer of filth from our spelunking foray, we headed south 20 miles to the Manresa Uplands Campground at Manresa State Beach, which acted as our headquarters.

Manresa, a hike-in/tent-only facility on gently sloping bluffs that overlook Monterey Bay, has the look and feel of a nature preserve. Looking down from the parking lot, one would be hard-pressed to even notice the picnic tables and fire rings that mark its 64 spots.

Campers pitch their tents in the wild grasses and are surrounded by orange and purple petals of burgeoning wildflowers. Of course, the average teenager has little appreciation for such things, and my band was no different. It was the camping itself -- not the location -- that interested them.

When we arrived on a sunny midweek afternoon, the campground was deserted, which only added to its natural allure.

Aside from our clamoring, there were no man-made sounds, just the chirping of birds and the hum of the surf below. For an Angeleno, such solitude can’t be oversold.

The boys lugged our equipment and erected the tents with due diligence and nary a complaint. Clearly, they were enjoying their time away from school and even their computers.

Before dark, we wanted to check out the beach, a quarter-mile walk away. To foster vegetation regrowth, much of the west-facing part of the campground is fenced off, and visitors get to the beach by using one of two sets of stairs at the northern and southern ends of park.

The beach was cool, crisp and uncrowded, and the teenagers drew pictures and concocted word games in the silty smooth sand.

At night, the kids’ attention turned to campfire building (“Is the tepee style most effective?”) and marshmallow roasting. (“Why does it take so long to get one golden brown but only an instant to turn one pitch black?”)

Our first full day was a near washout, as a springtime storm filled our tents with water and hampered our hiking plans. We instead drove around Santa Cruz (“Is that a hookah bar?”), watched DVDs and prayed for better weather.

The next morning, we awoke to clear skies and renewed enthusiasm for our campus excursion and our subsequent cave crawl.

When we returned to Manresa, the campfire/marshmallow routine began in earnest for a final time. As the kids reminisced about the trip’s highlights, I felt guilty about serving them hot dogs for the second time in three nights.

After all, they’re not in college -- yet.

tim.hubbard@latimes.com