Hollowed-out rock (Fallout: New Vegas)

Hollowed-out rocks are rocks that have been hollowed out and have items stored in them and are found across the Mojave Wasteland.

Mojave Wasteland

 * Abandoned Brotherhood of Steel Bunker: With the small cluster of rocks and shale on the slope leading up to the bunker grating.
 * Black Rock Cave: Just northeast of Helios One towards the satellite dishes. Directly east from the cave entrance. Has a heart painted on it.
 * Boulder Beach Campground: By the side of the road, north-west of the jetties, with "The Sun Is Killing Me" graffiti.
 * Bloodborne Cave: Just to the right of the cave entrance.
 * Bradley's shack: On the west side of the entrance, by the small valley landslide.
 * Broc Flower Cave: At the foot of the entrance slope, with "The Sun Is Killing Me" graffiti.
 * Camp Guardian: Next to the Camp Guardian population sign, at the base of the path up to Guardian Peak.
 * Cannibal Johnson's cave: Just to the right of the cave entrance.
 * Cazador Nest: Part of the rock wall, on the east side of the nest alcove, facing back towards the alcove.
 * Chance's Map: Adjacent to the dirt map, with "The Sun Is Killing Me" graffiti on it.
 * Cottonwood Cove: On the road between the two sets of crucifixion poles, with "The Sun Is Killing Me" graffiti.
 * Charleston Cave: Part of the rock wall, just to the right of the door, by the heart graffiti.
 * Crescent Canyon east: On the east exit slope, just after the rail bridge.
 * Crescent Canyon West: In the canyon, on the west exit slope, adjacent to a rusting car husk.
 * Dead Wind Cavern: On the south rock wall slope, around 20 to 30 feet from the entrance.
 * El Dorado Dry Lake: West of the Savaged brahmin, in the sands of the Dry Lake.
 * Fisherman's Pride Shack: By the campfire, north-west of the shack.
 * Fire Root Cavern: At the foot of the entrance slope, on the left.
 * Follower's Outpost: Built into the steps of the signal box structure.
 * Goodsprings cave: Just to the right of the cave entrance.
 * Hidden supply cave: To the left of the cave entrance, with the "no missile" graffiti.
 * Hidden Valley: West of the eastern bunker, with the "no missile" and heart graffiti. You may spawn in front of it when fast traveling to the location.
 * Jacobstown: Just outside the perimeter, to the right of the main entrance, where the super mutants stand guard. By the heart graffiti.
 * Jack Rabbit Springs: South of the pools of radiation, on the shore of the Dry Lake.
 * Lucky Jim Mine: Slightly beyond the shack, near the wooden cart.
 * Makeshift Great Khan camp: On the west side of camp, near the desert plants.
 * Morning Star Cavern: By the entrance to the cavern, by the bones and the explosive crate.
 * Northern Passage: On the eastern rock wall, near the grave and "The Sun Is Killing Me" graffiti.
 * Powder Ganger camp east: Next to a Honey Mesquite Tree, around 20 to 30 feet south of the camp.
 * Primm: Directly north of Lieutenant Hayes' tent. Climb the concrete wall attached to the cliff, near the entrance to the NCR side. It is attached to a large rock, near the scattered chems.
 * Primm Pass: Close to the brahmin bones, on the western end of the pass.
 * Remnants Bunker: About 10 feet north of the entrance, part of the rock wall.
 * Ruby Hill Mine: Part of the rock wall, just to the right of the door.
 * Searchlight East gold mine: Southeast of the entrance; climb on the pile of rock and shale to reach it.
 * Searchlight North gold mine: On the flat rock bank to the south of the entrance hole.
 * Silver Peak Mine: Part of the wall, just to the right of the shack through which you enter.
 * Techatticup Mine: To the right of the entrance, with the white blocks graffiti.
 * Tribal Village: At the start of the Ravine Path, close to the corpses and tents.
 * Vault 11: Just to the right of the entrance.
 * Vault 22: On the north bank, across from the "Keep Out" sign, by the entrance.
 * Walking Box Cavern: Around 20 to 30 feet east of the cavern entrance.
 * Yangtze Memorial: At the base of the south steps, with the peace symbol graffiti.

Zion Canyon
In total, in the Zion Canyon, you can find 15 hollowed-out rocks:

Low level

 * Court Fork Overlook - Behind the scenic overlook sign, south of the fast travel point.
 * Cueva Guarache - To the southwest of the cave, under the second bush of prickly pear, on the river bank between the rocks.
 * Sun Sentinels - On the very edge of a rocky ledge. From the point of quick travel south, just below and away from the prickly pear bush.
 * Clear Water Docks - Opposite the pier, on the other side of the river, to the northeast of the fast travel point.

Mid level

 * Three Marys - To the left of the entrance to the cave, behind the torch.
 * Three Marys - Gorge. Climb to the White Legs camp, located on a cliff, then until the next and follow along the rocks.
 * Angel Cave - Right above the cave, on a rocky cliff.
 * The Spine - In the distance along the southern edge of the map to the south-southeast of the fast travel point, on a cliff in a niche next to a Xander root.
 * Caterpillar's Mound - On a slope northwest of the fast travel point.
 * Caterpillar's Mound - On an outcropping southwest of the fast travel point.
 * East Fork Bridge - Next to the bridge, on an overlooking ledge immediately northeast of the fast travel point.
 * East Fork Bridge - Next to the road, immediately southwest of the second bridge to the southeast.

High level

 * Ranger Substation Eagle - At the dead-end of the gorge, in the opposite direction from the White Legs camp, southwest of the fast travel point.
 * Three Marys - Gorge. The last camp before the end of the gorge. Climb the cliff along the rocks.
 * Burial Mounds - On a hillside, west of the mounds, west of the fast travel point.