ROCKPORT – Exploring a cool, damp cave seems like just the ticket for escaping the hot, humid weather that has plagued Maine in recent days, but the members of the National Speleological Society who gathered in Rockport this week head underground as often as they can.

A mix of scientists, adventurers, conservationists and those who are just plain fascinated by the mysteries of underground labyrinths, the group held its annual convention at Camden Hills Regional High School.

Peter Jones, a potter from Camden who is co-chairman of the Boston-Cape Cod “grotto,” or chapter that includes Maine, helped bring the event to the midcoast region this year.

Maine is not known for its caves as are the Midwest, the Pacific Northwest and Hawaii, but Jones estimates there are about 130 caves here.

“There’s a few here in Camden,” he said while declining to name their locations. Members enjoy exploring what they call noncommercial caves – not the kind with a guide at the entrance and T-shirts for sale at the exit – and many have sensitive environments.

The NSS defines a cave as “a natural void in the ground that contains an area of total darkness on a moonless night,” Jones said.

Kevin Harris, 50, of Nashua, N.H., the other co-chairman for the New England area, said caves fall into two categories: those made by dissolving rock, called “solutional” caves, and those formed by lava or other forces.

“We have a fairly rich variety,” in New England, Harris said.

Bolder pile caves, such as those found in Grafton Notch, N.H., are typical of those here, as are sea caves such as those found in Acadia National Park.

A 90-page guidebook published for this year’s convention includes descriptions of the geological and meteorological forces that created caves in Maine. One article postulates that caves on Mount Desert Island were formed when the area was below sea level just after the glaciers melted.

Harris, who began caving in 1975 and has traveled all over the United States to visit caves, said one of the week’s field trips was to a sea cave on Champlain Mountain, some 220 feet above sea level.

Mike Hood, 42, of Dayton, Ohio, just ended his term as NSS president. He joined the group in 1982, though he began caving in 1974 as a teen-ager in southern Indiana, an area known for its prevalence of caves.

“Not a lot of people get to see or do the kinds of things we do,” he said in describing the attraction.

Fear of getting stuck between rocks does not bother him.

“You know your limits,” he said.

Hood has encountered bats and the occasional raccoon or skunk in caves. Other members have stumbled onto bears or bobcats, he said.

“You learn how to ‘read’ a cave” by noticing if leaves are stuck to its roof, indicating it sometimes floods, he said.

One of the most fascinating sights Hood has seen is a set of human footprints believed to be 2,500 years old in a cave in Tennessee. Because the cave, like most, was very humid, the footprints and the mud they are in were still wet, almost as if they had been made an hour ago.

Aurelia Nelson, 42, of Pleasant Hill, Calif., began touring commercial caves but soon discovered the NSS and joined in 1987.

She enjoys being a member of a “rock eaters” group, cavers who dig in search of undiscovered caves. The rock eaters look at the hydrology of a region, searching for clues such as water disappearing in the earth and emerging elsewhere.

“We actually discovered a cave that was three miles long” in upstate New York, she said.

A middle-school physical education and drama teacher, Nelson enjoys the “extended family” that is the NSS, and spends part of her summer vacation traveling to visit caves with fellow members.

In recent years, conventions were held in Kentucky and West Virginia; next year it will be in California. The NSS, founded in 1941, has about 12,000 members in the United States and other countries. Organizers said attendance in Rockport topped 1,000 late in the week, which is slightly less than a typical convention.

Originally a male-dominated group, the NSS now is made up of about 40 percent women, Nelson estimated.

For more information, see the NSS Web site at www.caves.org