There's a completely different world just under the surface in the Northern Shenandoah Valley. Multiple caverns offer guests entry into it.

• Skyline Caverns, on U.S. 340 near the entrance to Skyline Drive, attracts many visitors each year. Discovered in 1937, it is home to various unique and rare formations called "anthodites" -- six-sided crystals with white spikes that spread out in all directions. The growth rate of these formations, called "the orchids of the mineral kingdom," is estimated to be only one inch every 7,000 years. Other attractions include a miniature train ride and an Enchanted Dragon Mirror Maze. The caverns are open year round. Hours are June 15 to Labor Day 9 a.m.-6 p.m. daily, weekdays Labor Day to Nov. 14 9 a.m.-5 p.m. and weekends 9 a.m.-6 p.m., Nov. 15-March 14 9 a.m.-4 p.m. daily, and March 15-June 14 weekdays 9 a.m.-5 p.m. and weekends 9 a.m.-6 p.m. 635-4545. www.skylinecaverns.com.


• Endless Caverns, at 1800 Endless Caverns Road in New Market, is so called because the end has never been reported found. The caverns boast the largest lit sign in the United States, stretching 17,300 square feet across the Massanutten Mountain. Visitors are guided through a mile of underground passages. The cavern features rare blue stone and is a live cave with flowing water. A new RV park with 300 sites will be completed in 2009. Admission is $16 per adult and $8 for children ages 4-12. Hours June 15 to Labor Day are 9 a.m.-6 p.m.; hours Labor Day to Oct. 31 are 9 a.m.-5 p.m. Call for winter hours. 740-3993 or (800) 896-2283. www.endlesscaverns.com


• Shenandoah Caverns, at Exit 269 off Interstate 81, four miles north of New Market, has been open since 1922 and features a one-hour, one-mile tour of beautiful underground formations.


• Other attractions at the caverns include the American Celebration on Parade, an impressive display of parade floats, props and stage settings from American entertainment and political history, including floats that have been in the Rose Parade and in presidential inaugurations. Main Street of Yesteryear, which opened in 1996, exhibits an array of animated window displays from the 1930s and 1940s. The Yellow Barn, a whimsical exhibit of rural life, offers visitors shopping, exhibits, entertainment and delicious food all in a country atmosphere. There is no charge to visit the Yellow Barn. Admission to all attractions is $22. AAA and AARP members receive a discount. The caverns are open daily except Christmas. Hours are 9 a.m.-6 p.m. but may change seasonally. 477-3115 or 477-4300. www.shenandoahcaverns.com


• Crystal Caverns at Hupp's Hill Historic Park on U.S. 11 in Strasburg, includes an interpretive center that shows the historical use of the caves. Tours are available daily at 11 a.m., 12:30 p.m., 2 p.m. and 3:30 p.m. Haunted cave tours are offered on Halloween night. Flashlight tours are available. Admission is $10, and discounts are available. Inquire about special group rates. The caverns also offers Virginia's only karst interpretetive trail. The tour, which is free, outlines the footprint of the cave. Visitors learn about groundwater issues and can see the two different types of sinkholes, both of which exist on the property. Walking tour brochures are available at the ticket counter. 465-5884