A 16-year-old boy was wedged in a tight crevice in Skunk Cave in Iowa, just across the Minnesota border. For 12 hours, local and state authorities tried in vain to pull him out.

Hours after darkness fell, news of the trapped boy reached John Ackerman, who grabbed his gear and raced to the cave. Within 10 minutes of his arrival, the boy was free.

“I just knew what I was doing,” Ackerman, a 64-year-old cave explorer from Farmington, said about that 2001 cave rescue. “That one had a happy ending.”

But other rescue missions can be much more complicated, Ackerman said, such as the current effort to evacuate 12 schoolboys trapped in a cave in Thailand for two weeks.

The boys, ages 11 to 16, went cave exploring with their soccer coach after a game on June 23. Heavy rains flooded the cave, cutting off their escape and preventing rescuers from reaching them for almost 10 days.

Though the trapped team has been discovered alive and unharmed, rescuers face the complex and dangerous challenge of extracting them from the cave, especially with more seasonal monsoon rains thought to be on the way.

If flooded areas in the cave begin to rise, Thai officials said, trained divers would try to guide the team out — an approach many view as a last resort due to the twists of the tunnels and the boys’ lack of diving experience.

Authorities are also considering letting the team wait until flooding subsides and a safe way out is made available — a process that could take months — or drilling into the mountain to create an exit shaft.

Ackerman said he thinks the latter could be the best option. He’s drilled entrances into caves many times before with the assistance of cave radios, electronic devices that can beam a signal to the surface allowing those above ground to know where and how deep people are trapped.

With that information, rescuers can drill a hole right down to where the radio is located, slowing the drill bit before it punctures the ceiling so fast that it’s dangerous.

“I hope they can be rescued,” Ackerman said. “It sounds like they have all the qualified help they can find.”

For cavers, having the right gear and knowledge is important, Ackerman said. Explorers run into trouble when they enter a cave without heeding warning signs or forget to bring all the right equipment.

Ackerman has run into some sticky situations himself over the years. He’s been caving since he was a young boy and now owns 42 caves in southeastern Minnesota and northern Iowa, about 40 miles of subterranean tunnels. He said that when it comes down to it, it’s all about not taking unnecessary risks.

“Everything that we do is very calculated,” he said. “It may look crazy to the non-cavers, but when you’re experienced at climbing or diving or digging tunnels, it can be safe.”