In Hawaii, climbing Diamond Head is the height of delight

As dawn turns to sunrise, hikers arrive at Diamond Head State Monument.

There’s a toddler sporting tiny Nike shoes, an older couple gently holding a railing, and even two dogs nestled in carriers worn by their owners. They’re all here to traverse the 0.8-mile trail leading to the summit of what many consider Hawaii’s most recognizable landmark.

Diamond Head is a volcanic tuff cone formed some 300,000 years ago during an eruption. Inside lies a crater that stretches more than half a mile wide. The hike, in fact, begins on the crater floor. From there, visitors follow a gradually inclining – and then steep – path up 560 feet. Some pause sporadically to catch their breath, take in the view, or snap the all-important selfie.

Decades ago, Diamond Head served as a coastal defense system, hence the tunnels, bunkers, and lookout stations carved into the volcanic crater. Today, it’s a National Natural Landmark.

Melissa McElroy and Crystal Croteau, visiting from Florida, are among those who rest partway up the trail as their dogs peek out of identical carriers. It was the first hike of their vacation.

“We don’t get elevation at home,” Ms. McElroy says, acknowledging the challenging trek.