The Associated Press

OLIVE HILL, Ky. - Hundreds of adventure-seekers will get a glimpse this month into the underground world at Carter Caves State Resort Park.

Park officials are taking reservations to join excursions during the 22nd annual Crawlathon caving event Jan. 24-26.

The event is known to experienced cavers across the country, but also attracts plenty of newcomers.

"The attraction is exploring nature, and the challenge," said Coy Ainsley, naturalist at the park in northeastern Kentucky.

Mr. Ainsley expects at least 750 people to attend the event.

A guided trip through the "back door" of the park's Bat Cave, estimated at 2‡ hours of slithering and climbing, filled quickly, officials said.

Another tour, which features a John-boat ride across a large underground pool of water, has no spots left. Tours to lesser-known caves around the park are filling fast, Mr. Ainsley said.

Carter Caves started the event as a way to bring more visitors to the park during the winter.

Natural caves are unaffected by outside temperatures, hovering at a comfortable 56 degrees year-round.

Dozens of cavers, both locally and from other states, volunteer to lead the trips or conduct workshops on such topics as photography and cave mapping. Visitors can learn how caves are formed and what types of animals live in them, Mr. Ainsley said. Or they can simply enjoy the view of limestone stalactites and stalagmites.

"What this event has become is a forum for exposing all people to the highest level of caving science with world-class speakers," said Terry Waechter, president of ESSO Grotto, a Flatwoods-based cave club.

This year's speaker is Barbara Am Ende, who helped explore the mile-deep Huautla Cave System in Mexico in 1994.