Arroyo Tapiado Mud Caves

Useful Information

Location: Anza-Borrego Desert State. In the desert some 90 km easo of San Diego. Follow S2 form Agua Caliente Springs 7 km southeast. Turn left opposite a desert-suburb, may be signed as "Palm Springs" or "Vallecito Wash". Follow Vallecito Creek Road for 7 km, the turn left, 5 km to the cave. 4WD recommended, but 2WD with high clearance works fine.
Open: no restrictions.
Fee: free.
Classification: Speleologyerosional cave
Light: bring torch
Dimension: Carey's Big Mud Cave: L=300 m, VR=24 m.
Guided tours: n/a
Photography: allowed
Accessibility: no
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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The Arroyo Tapiado Mud Caves are located in the Californian desert. Arroyo Tapiado is Spanish for "walled dry creek". Mudstone or silt is a really soft rock, more like clay than real rock. The silt would quickly be washed away in humid climate, but in the desert, it stays for a long time at the surface. The rare rainfalls are often quite strong and produce mud floods, as the water mixes with the dry dust and silt and the mud flows down the canyons. In a small area, where the rock is silt and thus quite soft, the mudflows cut deep into the rock, and form slot canyons. If there is a crack or probably the upper part of the slot canyon collapses, a mud cave is formed.

Mud caves are really rare, first of all because there are not many places with silt on the surface. Then they are rather short lived, because the water created the caves sometimes in a day by eroding an enormous amounts of silt, but in the next rain they may collapse or be filled with mud again. And actually the mud is even in dry form so soft, there is a great danger the cave collapses by chance.

The whole area of the silt is full of slot canyons, natural bridges, and mud caves. There are about a dzen mud cave, among them Big Mud Cave, the only cave marked on most maps because of its size. Hidden Cave, is impossible to find without precise directions, hence the name. Chasm Cave is quite popular because of its beautiful skylight. The largest cave in the park is Carey's Big Mud Cave. A short cave which ends in a huge round room is Plunge Pool Cave.

And so we must warn you: this is not only the only place we know of where you can actually visit mud caves, it is also one of the most dangerous places we list. This is not a safe show cave, this are natural caves and because of the soft rock there is a high risk of collapse. Please follow the normal rules of exploring caves and be very careful. Do not go here alone, always go in a group of at least three persons. Tell someone where you go and when you will be back, so he can alarm rescue in a case of accident. In the cave take a helmet, headlamp, and at least two other light sources. Good walking shoes, long sleeves and long pants, overall if possible, gloves and kneepads are recommended. Also bring enough water, its the desert after all. For the dry dust we recommend a bandana or dust mask.

And the specialty here is: never walk on top of the caves, along the ridges. These hills are made of mud and are very unstable. The easiest was is to follow the canyon on the floor, the dry riverbed is easy and safe to walk. And a final warning: never visit the caves if it is raining, has rained recently or if rain is expected. During rain you would face deadly mud floods, after the rain the floor will dry partly, so you may walk until you hit a soft spot and get stuck in the mud.