Brinco Charco Azul, Cañón San Cristóbal- Barranquitas, Puerto Rico (photo by kachyblue on imgur) - San Cristobal Canyon is the only volcanic rift in Puerto Rico and is approximately 650 feet down to the bottom. The temperature at the top is considerably cooler than down in the canyon. The canyon is about 9 kilometers long. There are two rivers running through it and several waterfalls. It isn't easy to see. There is no built 'Tourist' access road, it is just there.