ST HELENA — The RMS St. Helena stayed tied up dockside in Cardiff, South Wales, for four days beyond her scheduled departure date. When eventually she sailed, she was hit by a Force 9 gale and unexpectedly high swells in the Bristol Channel. Most passengers, many of the crew and even the ship’s doctor kept to their bunks.

David Dinen, his youth and vitality supported by antimotion tablets, did more than stay upright. He paced the deck, adjusting to the ship’s rolling and pitching. He went down into the engine room to look and learn, though engines are not a particular passion of his. Looking and learning, though, are principles. He went up on to the bridge to watch and be instructed. A medical student from Philadelphia, he is the first in his family to be headed for a career in medicine. He intends to be a specialist pediatrician. “I like children,” he said. “I want to be able to set sick children up for healthy lives.”

At the ship’s first Atlantic Ocean port of call, the Spanish resort of Tenerife in the Canary Islands, of course David went ashore. He walked uphill through the town of Santa Cruz, where cobbled boulevards are set with open-air cafes, and jacaranda trees are heavy with lilac bloom. He visited the church of San Francisco, the botanical gardens, and the museum that retells 18th-century histories of battles and conquests and the mortal wounding of Admiral Nelson. “I’ll come back here one day and spend more time,” David declared.

When the ship crossed the line, David volunteered to be “tried” by King Nepture, found guilty, punished and thrown in the pool. At Ascension, he was one of the few passengers to attempt the difficult landing. From the ship’s anchorage, he went by ferry to the steep narrow steps cut into the seawall that give the only ocean entrance to the island. Swelling waves dramatically lifted and lowered the ferry boat. Landing meant jumping onto the steps at the height of a wave.

Ascension fed David’s curiosity. He heard the entrancing story of the green turtles that swim from Brazil, nearly 4000 km way, to this speck in the ocean where they find their beach, mate and lay their eggs in the sand. He learned of Ascension’s unique bird, the wideawake. He went on a road tour of the island, that is moonscape on the lower levels, where indeed the American moon buggy was tested, and that is lush and tropical higher up. He visited Comfortless Cove, and its sad little cemetery where long ago seamen who died from yellow fever were buried. Back on board the ship, he watched flying fish, leaping dolphins and spouting whales. Then he returned to his light reading, “Crash Course in Surgery.”

In his university, David happened upon a course on The Way of Tea. “On campus is a rebuilt tea house, and the teachers are from the Urasenke School in Kyoto,” David said. “Some of the tea bowls we used were made by former students. I really liked “cha-no-yu.” It was very relaxing from the stressful time of exams and getting ready for med school.” That particular interest, and the Japanese language study that in university he began with Eric Sackheim, former Tokyo resident, are on hold while his career preparations take priority.

David has been to St. Helena before. This remote and small volcanic pile in the south Atlantic Ocean, thousands of kilometers from nearest land neighbors in any direction, has no airport. Private yachts and occasional cruise liners may call, but otherwise the only regular carrier of people and goods is RMS St. Helena. The ship visits about once in two weeks, except when, four times a year, she is on the long Cardiff-Cape Town route. Then St. Helena is cut off for six weeks at a time.

“Three years ago I booked this voyage without knowing anything about St. Helena,” David said. “I’d never heard of it. I wanted to go somewhere off the beaten track, and travel by ship but not a cruise ship. St. Helena is still an isolated place, a strange mix of being modern and in the past. It is one of the few places in the world possible to reach only this way. The islanders are friendly, that’s the big thing. I’m still in touch with the friends I made before, officers and crew of the ship then.” On St. Helena for this longer stay, David is to study in the local hospital, “seeing everything that the physicians on the island do. I think some British medical students have done this before, but probably I am the first American,” he said.