The Tongva Hills Cave is a small cave burrowed in the hills of the Tongva Valley. The cave is located north of the second stream running through the valley, in about the dead center of the Tongva Valley region. The cave begins with a tall crack in the mountainside before recessing a couple of feet into the wall. The cave is completely barren, except for a pile of rocks and a Spaceship Part. No animals or pedestrians can be seen entering or exiting the cave.
The Tonga Hills Cave is associated with many in-game myths.
The primary myth reported in the area is the Tongva Hills Creature, with players claiming that the cave serves as the home of the beast. The surrounding area has a stream and lots of wild animals, so a predator living there isn't too far fetched. There aren't any known sightings of the creature specifically appearing inside the cave, instead, the cave is just the subject of fan rumors.
Another myth is Native Americans. Players have reported strange sounds coming from the proximity of the cave, which is also claimed to be the home of one of the Natives. The walls of the cave have occasional black grime on them, with players attributing this to a fire that was lit by a native. Additionally, the Spaceship Part located inside the cave has been connected to the real-life ancient aliens theory.
The cave was also featured in the Red Dead Redemption 2 Treasure Hunt in GTA Online. One of the clues for gaining the prize was inside, and a semi-nude mutilated body would be found.