Big Bend Ranch State Park Ojito Adentro Mining District Circuit
Mercury mining roads through volcanic desert canyons
The Ojito Adentro mining district deep in Big Bend Ranch State Park preserves a maze of 1940s mercury mining roads that snake through hidden canyons and over volcanic ridges where quicksilver operations once extracted cinnabar ore. These rough mining tracks drop through technical rocky descents into Fresno Canyon and climb back out through loose volcanic scree, passing collapsed mine shafts, rusted equipment, and stone foundations where miners lived in isolation. The route connects multiple mining sites including the old Ojito Adentro village ruins and the Fresno Mine workings.
This is expert-level terrain demanding experienced drivers, rock sliders, and aggressive tires for the loose volcanic climbs and sharp limestone descents. Summer is brutal – attempt this October through March when temperatures drop below furnace levels. Camping permit required through Texas State Parks, plus entrance fee. No water available – carry minimum two gallons per person per day. Cell service nonexistent. You earn every mile in this forgotten corner of the Chihuahuan Desert, but the solitude and mining history make it worth the punishment your rig will take.
Trail Specs
| Difficulty | Expert |
|---|---|
| Trail Type | Technical 4x4 |
| Surface | Rock |
| Features | High Altitude, Historic, Remote |
| Length (miles) | 35 mi / 56.3 km |
| Duration | 2-3 days |
| Max elevation (ft) | 4800 ft |
| Best season | October-March |
| Minimum vehicle | Modified 4WD with rock sliders |
| Nearest town | Presidio, Texas |
| Land manager | Texas State Parks |
| Permit required | Yes |
| Cell service | None |
| Water crossings | No |
| Dispersed camping | Yes |
| Official sources | tpwd.texas.gov |
| Start coordinates | |
| End coordinates | |
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Location
Trail Conditions
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Frequently asked questions
Can a stock Tacoma or 4Runner run this trail, or does it actually need to be modified?
A stock rig will get hurt out here. You need a modified 4WD with rock sliders at minimum — skid plates, a lift, and all-terrain tires are not optional. The volcanic rock is sharp and unforgiving, and recovery from a torn-up undercarriage this far into the backcountry is a serious problem.
What's the trail like in summer — is it even worth trying?
Summer in the Chihuahuan Desert means triple-digit heat, flash flood risk in the canyons, and zero shade. The best season is October through March when temps are manageable and the canyon trails are drier. Running this in July is a bad idea unless you enjoy heat stroke and baked electronics.
Do you need a permit to run the Ojito Adentro circuit, and is there a fee?
Yes, a permit is required through Texas State Parks (TPWD) — you cannot just drive in. Contact Big Bend Ranch State Park directly or book through the TPWD site at tpwd.texas.gov/state-parks/big-bend-ranch. Fees apply, and access is controlled, so plan ahead — walk-up permits are not guaranteed.
What's the hardest section of the trail and what makes it technical?
The rocky descents into the volcanic canyon sections are where rigs take damage — loose basalt over steep grades with no room to correct if your line is off. Ledge drops and embedded rock fields require slow, deliberate wheel placement. One bad line can put a rocker panel or diff into the rock with nobody around to help.
How far is the nearest gas from the trailhead, and is there water on the route?
Presidio is your last real fuel stop before heading in — top off there, no exceptions. There is no reliable potable water on the route, so carry all you need for 2-3 days plus emergency reserve. Cell service is completely nonexistent on this trail, so your communication plan needs to be sorted before you leave pavement.
Trail track
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