EXTREME FLASH FLOODING AND HYPOTHERMIA DANGER
DURING THE SPRING, SUMMER, FALL AND WINTER MONTHS
ENTER AT YOUR OWN RISK
The Black Boxes are a primitive, backcountry experience. There are no signs or marked trails beyond the trail head. Your route finding, canyoneering skills and equipment must be up to the task.
During the spring, summer, fall and winter, there is an extreme danger of flash flooding and hypothermia. Even if it is not storming in the immediate area, storms originating near the mountains can cause flooding that will come down through the Black Boxes. Summer showers can raise the flow in the Black Boxes from less than one cubic feet per second (cfs) to over 2000 cfs in under an hour.
Canyoneering the Boxes requires hiking, floating, wading, scrambling and rappelling. Immersion hypothermia is a real danger, even during the hottest summer days. The sun does not reach the river due to the high canyon walls and the topography dictates that canyoneers spend the majority of their trip immersed in water. Plan on 12 hours for hiking the upper box and at least eight hours for the lower box. Many parties have been stuck in the canyon overnight because they got a late start.
Both river sections are far from emergency help. Search and rescue is difficult and costly to organize due to communication problems and access into these steep canyons. Cellular phones do not work in the Black Boxes. Your rescue can put local volunteers (people we know) in danger.
For information about the San Rafael River above the Black Boxes go to KNOW BEFORE YOU GO: FLOATING/HIKING/HORSEBACK RIDING THE SAN RAFAEL RIVER by clicking here. Be aware of Flash Flood Danger.