The hard way:

The world for this level has a single OOB. The only exit I could find was beside the Emily, the large boat aground out in the harbor. Head out the pier leading to the boat. Jump onto the boat, using a nearby box if necessary. On the landward side of the Emily, there are some large rocks right alongside and beneath the boat. Toss some of the boxes aboard the boat onto the large rock that is right next to the side of the boat. Jump over onto that rock. Turn on the "bones" cheat. Move parallel to the boat, in the direction of the stern. Note that you are actually standing on a flat platform. It doesn’t correspond that well with what you normally would be seeing, the top of the rock. The rock doesn’t look flat at all, and the extent of the platform doesn’t exactly follow the extent of the rock. Drop a large box or several boxes over the edge (again, facing toward the stern). Save your game. Step off the rock and fall on top of the box or boxes. (This is fatal about half the time.) If you survive, immediately save the game again, because this area is covered with invisible "electric fences."

The waterline should be just a couple of yards to your right. One such fence lies there, running parallel to the harbor bluff. Another lies about 20 yards or so to your left, also running parallel to the bluff. Head east, parallel to the bluff, between the two wires. After you pass under another arm of the same pier structure, the waterline moves landward. But the invisible fences surrounding you do not. Enter the water and keep heading east. The water will eventually disappear and you will seem to be walking on the sandy bottom. Save your game periodically, as you may still run into a fence. Eventually the land cuts across your path (about 50 yards or so past the gate where the level started), and you can safely come out of the water. There’s a low ridge directly to your left with a pronounced v-like gap in it.

After leaving the water, move inland in a northerly direction, toward the small ridge with the v-like gap. Go through the notch. Head a bit northwest and check out the outside of the gate where this level starts. There isn’t much interesting to see far from the playing area, so I would recommend just exploring around it. You can go all the way around (but give the end-of-level area a wide berth). On the west side of the playing area, there is a place where you can get on top of invisible terrain that overlooks the lab complex. You can get a great view from up there. Then continue in the direction of the Harbor. You can also get a good view overlooking the woods west of the Harbor. You can then make your way back into the water and back to the Emily, though there is not really much reason to do so.

Near the end of the normal game, you can gain entrance to the Computer Lab by entering "kandar" into the keypad. This was the "back door" that Hammond speculated Nedry had set up. [TSOrd - And, incidentally, is also the keycode present on the pad in Hammond's office. I think the designers intended for people to figure out Kandar (426327) but it was too hard a puzzle in testing so they put in the pad. The pad made it too easy. :( ]

If you go to the left-most section of the pen, there is a bent steel girder. Pick it up and take it over to the slope (it’s surprisingly easy to handle - grasp it on one end, with your arm parallel to the girder). If you place it right, you can walk or run up it to the area overlooking the pens. You can’t go very far, because of the invisible terrain. You can get to an area just beyond the pen wall on the end-of-level side. Drop down there. Walk over to the door that you would normally come out of. Face away from the door and the wall. Note your location and facing coordinates for later reference.

The basement: From the tidal flat below the Emily, head east (-1, 0) until the large offshore rocks are on your right. Then turn south (0, 1), pass by or through those rocks, and continue to and just past the edge of the bottom terrain. Turn left and head due east again, being careful to stay on the basement level. When your first location coordinate reaches about -350 yards, turn left again and go north (0, -1). Again, be careful to stay on the basement. Once your second location coordinate drops to about 900 yards, you should see the clump of tree objects up ahead. The various clumps of objects are generally east of the summit. You’ll encounter the following ones at these approximate locations:

Boxes, of many types: -351, 302, 1.4

Trees: -455, 314, 1.4

Guns: Not found

Dinos (2 t-rexes, a steggie, a trike, and a raptor): Near -20, 0.0, 1.4 (under the north edge)

Octahedron: Not found

Some of the boxes I found are not like any that I saw in the playing area. Some have lids and can be opened. Some appear to be charred. There are trunks that open. Off farther in the distance (to the northwest), you can see another clump of objects. These are the dinos. You can’t get too close to them, because they are actually situated just under terrain. Approach too closely and you’ll be teleported up. Also, there is a corner of the terrain that you can’t see between the boxes and the dinos. Go farther north, then west. Standing just a bit back from the rear of the dinos, shoot them. They’ll pop up onto the terrain element. Then you can continue farther west and go for the big auto-teleport-up to reach the summit. You can make this maneuver because the mountain is only half represented in this level world. That is also true only in the case of the demo level.