Not easy to find, cross over Commercial avenue under 376 bridge, head up to the left. You can enter either by taking the major trail to the right or up the single track to the left, a steep climb that then puts you in to the woods again. Either way, once you climb up to the left,exit the wooded area and you'll get to the large, wide open area. Lots of garbage, looks pretty barren. Swissvale will be on your left, view to Summerset housing on your right. If you head to the right side of the open field you will see a rough ridge that lines the hill. Enter the ridge anywhere and head parallel to the Summerset view. That part of the trail is pretty rocky, quick up a downs. At the end of the ridge, head left into the woods again and you will see a trail entrance straight ahead. This will put you into the woods and the main part of Crater trail. Pretty easy to follow the loop from there. the end drops you down to a main trail that connect back to the main entrance under the 376 bridge. Good luck.