Within often small borders, an island may contain a continent's worth of diversity. A recent one-week sample of Japan's south islands illustrated this perfectly.

Although I had visited Japan a number of times over the years, I had never departed the mainland, as the Japanese call Honshu, the largest and most populous of Japan's four main islands. The others — Hokkaido to the north, and Shikoku, Kyushu and the islands of the Inland Sea to the south — are Japan's "neighbor islands."

The more I read of these islands during the long flight from Honolulu to Tokyo, the more appealing they sounded, promising a glimpse of a timeless Japan, still largely rural, where tall forests cling to the deeply creased landscape and active volcanoes heat water in bubbling hot springs. They were also home to grand medieval castles and famous battlefields, impressive gardens and majestic temples that are renowned places of pilgrimage.

Departing from Tokyo's recently rebuilt, user-friendly Haneda Airport, I flew about 400 miles south to Takamatsu, a city on the island of Shikoku that faces the Inland Sea and the island of Shodoshima, the first stop of a three-island visit with a group of like-minded travelers. Connecting from airport to port by taxi, I transferred to a jet boat for the 30-minute trip to Shikoku, islands emerging from a bright haze as we sped by.

At 100 square miles (about 25 percent smaller than Lana'i), Shodoshima is the second largest of the 800 islands rising from the waters of the Inland Sea, a depression in the volcanic landscape between Honshu and Shikoku breached by the waters of the North Pacific. It is renowned for its hot springs, or onsen, ruggedly scenic landscapes and historic Buddhist temples and shrines. Seven small ports offer ferry service between Shikoku and Honshu.

Despite its small size, Shodoshima projects grand scale, most impressively in the two-mile-long Kankakei, a ravine that dissects the island, providing a hiking trail amid dense foliage and rocky pinnacles. Short of time, I opted for a 7-minute tramway ride that carried us through the most dramatic portion of the ravine.

The island is home to hundreds of monkeys — fascinating, unkempt screechers with bulbous red butts who bully one another with frightful attacks. The dominant males don't even spare nursing mothers in their pursuit of the food handouts that coax them out of the wild at the Chosikei Monkey Reserve.

Shodoshima also has a number of historically significant Buddhist temples and shrines, including Nishinataki, 42nd — and perhaps the most impressive — of the 88 sites on Shodoshima that attract 50,000 pilgrims each year.

Built into a nearly vertical mountain landscape 1,200 years ago, Nishinataki is reached by a switchback road that makes its way through a forest of giant ash, poplar, eucalyptus, cedar and pine, an occasional long view revealing the distant coast. A steep series of stone steps leads to the temple and the tunneled entrance of a small cave in which the revered monk Kukai meditated and taught in the eighth century.

I purchased several small prayer paddles on which the names of loved ones have been written, selecting pleas for good luck, good health and success at school from choices suited to every occasion and need. A tall, youthful, saffron-robed monk led us into the meditation cave, holding the prayer paddles in his hands for the ceremony to follow. Another monk carried a tall drum, similar to the sacred pahu that accompanies the hula.

The fire's glow lit the room, the flickering yellow light revealing a fierce-looking Buddha. The ceiling was black with the smoky remains of fires that have burned here for centuries.

Seating himself before the fire, the first monk broke the silence with a soulful prayer intoned as the first of the paddles was placed in the fire. The flame shot upward as the paddle caught fire, prayer and drumbeat echoing off the cave's rocky, soot-stained walls. The ceremony ended after a dozen other paddle offerings, the priest and drummer both in a heavy sweat, the audience in a respectful silence. I exited the cave stunned by the sunlight and the lingering impact of the ceremony.

ANCIENT WATERS

For three nights, I was based at the Olivean Resort, about 30 winding minutes from Nishinotaki. It's a perfect base for a Shodoshima visit, a welcome place to return to after a day exploring, particularly when the setting sun silhouettes the islands and promontories of the Inland Sea. And there's the onsen, a soothing retreat, with water said to be 300,000 years old, piped to indoor and outdoor soaking pools from hot springs 6,000 feet below.

"Dig down anywhere in Japan and you'll find a hot spring," a Japanese friend had told me. This proved true as I traveled from island to island. Each onsen had its own style, from the 19th-century feel of the Dogo Hot Springs in Matsuyama to the rustic privacy at the Ryokan Hanamomiji.

I found myself heading to the onsen several times a day, quickly becoming addicted to the soothing warmth and the Zen-like quality of the cleansing ritual that precedes a soak in the mineral-rich waters. Many of my most vivid memories from the days that followed, here and on Shikoku and Kyushu, were onsen-inspired. Moments of contentment are vividly etched into the memory: sitting in a rock-lined pool fed by a bamboo spout, water to my shoulders, steam rising in cursive patterns, distant mountaintops in silhouette as an orange sun slips behind low clouds; soaking in hot-spring warmth, protected from the chill mist carried by a breeze fragrant with cedar; relaxing under a midnight sky after an aggressive shiatsu massage, searching the midnight sky for a familiar constellation.

BEAUTIFUL IRIS

As my tour group departed Shodoshima blue skies prevailed, fog burning off to reveal Shodoshima's green slopes. Other smaller islands came into view as we skimmed the waters of the Inland Sea on the 30-minute trip to Takamatsu, a city on the northeast coast of Shikoku, smallest of Japan's four main islands.

Like Shodoshima, Shikoku is renowned as a place of pilgrimage, also home to 88 Buddhist temples. I took a day trip to the most famous of these, the Kompira-san in the town of Kotohira, about an hour inland by bus. There are 785 stone steps from the street to the main sanctuary, and another 583 if you go all the way to the summit temple. The way is lined with countless votive tablets and stone lanterns, offered over the centuries by pilgrims seeking help or offering thanks. En route, tall trees provide an inspiring canopy.

Our afternoon return to Shodoshima left us time to visit the towering, hilltop statue to Kannon, the revered goddess of mercy and compassion. An elevator took us to the shoulder-high lookout offering panoramic views of Shodoshima and the Inland Sea.

The next morning we returned to Takamatsu, the first stop on a daylong drive across Shikoku that would get us to the city of Matsuyama. Takamatsu is renowned for Ritsurin Park, a haven of meandering walkways, ponds, and artfully landscaped grounds that is considered one of Japan's most beautiful gardens.

On the morning I arrive, giant irises are in full bloom, deep purple, pale blue and white varieties that trigger a childhood memory of when I was first dazzled by the intensity of iris colors and the intricacy of their floral architecture.

I am not alone in my admiration. The Japanese revel in such idealized moments, when fruits are at their best or flowers at their most perfect. Just as cherry blossoms are celebrated as a symbol of early spring and chrysanthemums are symbolic of autumn, the iris epitomizes the exuberance of summer.

We stop by the Kikugetsutei, a historic teahouse, all shoji screens and ponds, for a modified tea ceremony. Outside, a fleet of giant koi swims through the dark waters, gliding by in patterns of iridescent orange and red, silver and gold. A meditative calm prevails as I take my next sip of tea.

The garden proves an appropriate introduction to Shikoku, an idealized version of its wild, forested landscape. Departing the garden on a luxury motor coach, we set out on a day trip across the island, with the city of Matsuyama our late-afternoon destination.

Departing the freeway, we headed into the mountains, rewarded with lushly green alpine views and the turquoise waters of the Yoshino River, Further into the mountains we crossed an ancient vine bridge, now reinforced by metal cables, that sways above the river, followed by fresh fish for lunch at a popular riverside restaurant short on atmosphere but tasty enough to compensate.

Winding our way through the mountains back to the freeway, we spent the next three hours heading west, skirting the Inland Sea, idyllic views alternating with the intrusion of the giant pulp mills that are an extension of the island's expansive forests. It's late afternoon when we pull into Matsuyama, an attractive city renowned for its hot springs and castle.

The Dogo Hot Springs, the oldest in use in Japan with a history dating back 3,000 years, provides an architectural landmark at the center of town. The current bathhouse, complete with private quarters for the imperial family when they visit, dates to the late 19th century. People in clogs, robes and towels — onsen attire — slowly make their way from the Dogo to their hotels, many of which are also onsen.

Rising at dawn the next morning, I set out for a nearby temple as Matsuyama came to life: neatly uniformed children on their way to school, delivery boys on bicycles, businessmen in Mercedes heading to work. After a hearty breakfast, we headed to the airport and the short flight to Kumamoto, on the island of Kyushu.

MEDIEVAL CASTLES

Kumamoto is home to one of Japan's 48 magnificent medieval castles. Largely rebuilt after falling into disrepair following a devastating fire in the 19th century, its earliest intact building, a seven-story tower, dates to the 15th century. Precision-cut rock walls form a monumental platform for the castle buildings. The walls rise from a grassy depression that was once a moat. I would return here on the last afternoon of my southern islands visit, lying on the lawn that surrounds the castle's monumental cut-rock walls.

Kyushu's volcanic landscape is reminiscent of the Big Island — fields marked by grass-covered cinder cones, with an active summit caldera. As with Kilauea and Haleakala, the summit of Kyushu's iconic Mount Aso, renowned for its five distinct peaks, is the centerpiece of a national park, which I visited on my first morning on Kyushu after spending a night at Hanamomiji, a luxurious countryside ryokan about 90 minutes from Kumamoto.

Hanamomiji is a 21st-century ryokan where tradition and contemporary comforts are reconciled, with four-room suites that offer Western and tatami-mat bedrooms and hot-spring-fed soaking tubs. I preferred the rock-lined, outdoor onsen just uphill of the ryokan.

Dinner that night proved a sumptuous feast hosted by the youthful owner of the ryokan. One course followed another in elegant sequence, including delicacies, such as horse-neck sashimi, that demanded gustatory courage on my part.

While population pressures are evident in some places on Kyushu, much of the island retains a rural, often wild, feel, with terraced rice paddies and large stretches of pasture alternating with dense stands of cedar, the same sugi trees brought to Hawai'i from Japan that now thrive in Koke'e on Kaua'i and at Polipoli Springs on Maui.

In this bucolic setting, traditional Japanese culture flourishes, both in the architectural style of rural homes and in volunteer theater ensembles. At the Seiwa bunrakukan (puppet theater), nearly life-size, costumed puppets, each controlled by a trio of puppeteers, presented a brilliantly choreographed performance. Dressed entirely in black in an effort at anonymity, the trio moved as one. While one puppeteer held the levers that controlled the right arm and head, the second manipulated the left arm, with the third moving legs and feet. The story was of love and loyalty, the narrative and dialogue accompanied by music.

Dinner that night was in a 150-year-old home, its rooms and gardens now a restaurant where a dozen courses followed in elegant sequence. Sake, the social lubricant in often-formal Japan, flowed, adding high spirits and loud laughter to a meal that lasted more than three hours.

The week had gone by too quickly, the way it usually does when travel is filled with unique experiences. I was booked for a flight from Kumamoto to Tokyo, landing at Haneda about 90 minutes later, making an easy bus transfer to my Tokyo hotel and the urban adventures to follow. I left Kyushu wishing I'd had more time but satisfied that my week-long visit had been charged with the authenticity and good times that make travel so rewarding.