SIGGRAPH 2002 Lab Trip

July 27, 2002

Text by Natasha Gelfand
Pictures by Natasha Gelfand and Leslie Ikemoto

  The original plan for this year's post-Siggraph trip was to go tubing (or "toobing" as they say in Texas) down the Guadelupe river. Unfortunately, several weeks prior to our trip, a hard rain hit south Texas, causing catastrophic flooding in the Texas Hill Country. The picture on the left (from shows the Guadelupe River near New Braunfels, exactly where we wanted to go tubing, during the flood. The house in the foreground is not just flooded, it's actually floating down the river. By the end of July the local rivers were still in flood state and full of debris, making them unsafe for river running. With a heavy heart we had to accept that the tubing trip had to be canceled.
So, instead of going on the water, we went underground, on a spelunking adventure through the limestone caves near San Antonio called Natural Bridge Caverns. Most of us have not been caving before, and some were a little apprehensive about going into a damp, dark, scary cave, but Marc provided the necessary encouragement.

Billy: "I'm afraid of heights. I am claustrophobic. How am I going to survive caving?"
Marc: "You have to be tough..."

  We assembled early on Saturday morning and drove to the caves, which are half hour from San Antonio. We signed up for the "adventure tour" which meant we were going to be exploring the undeveloped South Cavern, which has been opened to the public only several years ago. Before descending into the cave we were outfitted with our caving gear: coveralls and gloves (the floor of the cave is covered with sticky mud), helmets with flashlights (the caves are unlit), and harnesses (we were going to be rappelling down a rock wall along the way). Posing in spelunking outfits, from left to right, are Vaibhav Vaish, Natasha Gelfand, Marc Levoy, Ren Ng, Billy Chen, and Leslie Ikemoto. Notice how clean everyone is. That is about to change.
  The South Cavern can be entered in two ways: by descending down a flight of steps, or by being suspended from a rope attached to your harness, and being lowered through a well shaft into the cavern. Not knowing what we were getting into, we all chose the second option.

That seemed like a good idea, until we actually saw that we had to get through. The shaft is only 22 inches wide, and 160 feet deep, and the descent would take about 4 minutes! Undaunted, Vaibhav volunteered to go first, and disappeared down the rabbit hole. One by one, the rest followed.

  After several minutes of traveling down the narrow well (personally, I kept having scenes from the first chapter of Alice in Wonderland go through my head while going down), the descent ended on a ledge in a large room, where our guide helped lower us down to the floor and unhook the rope from the harness. On the left, Leslie is looking happy to be done with the descent.
    The climate inside the cave was actually quite pleasant, 70 degrees and 99 percent humidity (it stays the same throughout the year), a nice break from the heat in San Antonio. The cavern system consists of a set of rooms connected with passages, most of which were pretty large, allowing us to just walk along enjoying the limestone formations around us. On the left is a set of "soda straws", tubes of limestone with water flowing through the middle. On the right is a flowstone formation appropriately called a "fin".
    In the middle of our tour we had to rappel down a pile of rocks about 45 feet high. On the left, Marc is being instructed in the art of rappelling. On the right is the view up from the bottom of the wall, as Ren is showing us his climbing expertise. Bright spot in the upper right is one of our guides looking down at him.
  The cave dead ends after half a mile in the "Fault Room" at the depth of 230 feet below the surface. This room has lots of impressive formations, including one the the longest soda straws in North America - 14 feet in length. After taking a break in the Fault Room we retraced our steps back to the start and walked out of the cave using the entrance that we skipped on the way in.
    We got a few comments about our appearance from the other tourists as we were walking back to the visitor center.

Y'all look a little muddy. -woman sitting near the visitor center
Look, mommy, dirty people. -little girl

Although most of the passages in the cave were wide enough for walking, two places required crawling on hands and knees, making us covered in mud. On the left are the before and after shots of Leslie's and my hiking boots.

  Proof that nobody was left behind in the cave. Front: Natasha, Marc, Vaibhav. Back: Leslie, Ren, Billy.

Click here for more pictures from this trip.