NOTE: This information comes from the trail map I have, which was last revised in 2000.
Purgatory Chasm State Reservation is made up of the Chasm area, several trails that go around the chasm and through the surrounding woods, a playground and a ballfield, and picnic areas which include picnic tables, a pavillion and charcoal grills.
There are 5 hiking trails, ranging in length from 1/4 of a mile to 1 mile. There are also woods roads that are used for hiking. The Chasm Loop Trail is 1/2 of a mile. It runs straight through the center of the Chasm, and then winds its way up along the top (southeastern side) of the Chasm. Charley's Loop is a full mile, and starts off following the top (northwestern) edge of the Chasm - there are some great views from over here. This trail contines around the far side of the Chasm, away from the edge of the Chasm. Spring Path is on the other side of Purgatory Road. It winds by the playground and the ballfield, and also the ranger station. It is 1/4 mile long. Further north away from the Chasm area you will find Old Purgatory Trail (3/4 mile) and Little Purgatory Trail (1/2 mile). Check out this map of the Chasm area. (You'll have to make do with the 1996 map until I can scan in the 2000 map, sorry! The Chasm hasn't changed much.)
Within the Chasm itself there are several landmarks: The Coffin, Fat Man's Misery, Devil's Corncrib, Devil's Pulpit, His Majesty's Cave, and Lover's Leap. Many people enjoy the variety of small caves and crawl spaces that the Chasm offers. With a permit, climbers can scale the rock faces of the Chasm.
This is definitely a place where you want to wear good shoes - the rocks get slippery when damp. Also, bring bug repellant. Young children may have a tough time taking the trail through the Chasm - some of the jumps are pretty steep. Bring your flashlights for cave crawling! Leave your alcohol at home - the park doesn't allow it. The Chasm is open all year round (I hear the ice views are spectacular in February) from sunrise to sunset, and is located about 20 minutes south of Worcester off of Route 146. Enjoy yourselves!