MAJURO, Marshall Islands >> It was clear right away it was a tuna swimming past because of the distinctive bumps along its back that lead to its angular tail. And what a whopper. It was about the size of a small person, and seemed unbothered by me bobbing just a few feet away.

It was my second dive, with a colleague, in the remote Marshall Islands, midway between Hawaii and Australia. There’s little tourism here, but plenty to see below the surface. During our first dive, in the Majuro lagoon, we’d explored a sunken plane, helicopter and ship in water that was warm and crystal clear.

We started with the plane, an old DC3 resting on the sandy bottom at a shallow depth of 10 to 20 feet, making it accessible for novice scuba divers and even experienced snorkelers.

Fish darted about what were once the cockpit controls, and we could see an old strap still hanging inside a window. Along the side we could make out most of the lettering: Sea Star Pacific.

A little deeper, the helicopter was shrouded in seaweed and tube-shaped growths. Deeper still was the ship, its rooms and decks accessible with careful maneuvering and the aid of an underwater flashlight.

Our guide, Hiroaki Ueda, explained the wrecks had been towed there for divers to enjoy.

Ueda has completed some 4,000 dives all over the islands, he said, and loves the endless color and life he finds in the coral.

But climate change is having an impact throughout the Marshall Islands, which are vulnerable to rising seas and storm surges. Last year, Ueda said, he saw extensive coral bleaching, coral weakened and turned white by warmer water temperatures.

He took us outside the lagoon to the oceanside coral for our second dive. This time we went deeper, about 100 feet, along a coral bank that dropped away steeply into the abyss below.

A turtle swam lazily along until it seemed to sense it was being cornered and darted away.

Ueda runs his business, Raycrew, from the Marshall Islands Resort, one of just two Western-style hotels in the capital, Majuro.

Life on the islands is slow-paced, and sometimes things like the Internet, or the electricity, don’t work. In populated areas the lagoon is ringed with trash, although some young activists are organizing drives to clean it up.

Most scuba divers that come to this part of the world tend to head to the World War II wrecks found around Palau and the Micronesian island state of Chuuk. Some make a stop at the Marshall Islands along the way.

The Marshall Islands also have stunning wreck diving in the Bikini Atoll, although getting there is only for the adventurous.

From April through November the Bikini government helps organize a handful of trips in which divers live aboard a boat for two weeks and are told of the atoll’s history.

After the war Bikini was at the center of the U.S. nuclear testing program. One of those tests sank the USS Saratoga (CV3), an aircraft carrier that is now a favorite for divers. It remains unsafe to eat fish from the Bikini lagoon. Perhaps ironically, that has led to an explosion of sea life there.

IF YOU GO …

MARSHALL ISLANDS

>> Getting there: United is the only major carrier serving the Marshall Islands, departing from Honolulu just three times each week.

>> Where to stay: Marshall Islands Resort is in the capital, Majuro (marshallislandsresort.net). Raycrew dives is in the hotel complex, charging about $75 per dive.