Thrillseeker jumps into El Sotano de las Golondrinas, so deep CLOUDS form inside Dave Bunnell, from Delaware, has traveled to 18 countries to dive in caves but his favorite is El Sotano de las Golondrinas, the Basement of Swallows, in San Luis Potosi, Mexico A thrillseeker who has traveled the world to dive into its dingiest caves has shared stunning photographs of his favorite one yet - a 1,200-foot-deep hole in Mexico that is so deep, clouds form inside. Dave Bunnell, a 61-year-old adrenaline junky from Delaware, has traveled to 18 different countries to take on dozens of the world's dingiest pits - and his favorite is Mexico's astonishing El Sotano de las Golondrinas, also known as 'the Basement of Swallows', in San Luis Potosi. These stunning images of the cave - one of the world's most dramatic free fall pits and a natural wonder than attracts thousands of cavers each year - show the moment he and his fellow divers plunge into the cave, passing through the clouds inside. Stunning: Cave diver Dave Bunnel, 61, captured these stunning images of him diving into Mexico's El Sotano de las Golodrinas, The Basement of Swallows Getting there: Cave divers plunge through the clouds that have gathered inside the cave and head to the bottom of the 1,200-ft-deep hole Dave, an avid photographer, said the spectacular clouds, which form when humidity comes into contact with colder air, provide a perfect opportunity for him to take stunning pictures. He set up equipment on the cave floor below to capture the remarkable images. 'I started caving when I was 21, as part of a university outdoors club - I'd already been backpacking and rock climbing with them,' he explained. A couple of girls I was interested in were going caving, so I signed up and never looked back. I've since traveled all over the world, enjoying some of the most beautiful natural sights on the planet. 'It's such a different world it sometimes seems like being on another planet. So the other-worldliness of it, and that you never know what may lay around the next corner, when exploring a new cave, even a small one can give you these feelings like no other. Breathtaking: Bunnell, who has been cave diving for 40 years, painstakingly set up cameras to capture the moment he and his teammates plunged inside Massive: A close-up of the cave floor shows figures of the climbers gathered at its base, revealing just how large the cave is The pit was first descended in December of 1967 by a trio of Americans. Its total depth is 1,638ft although the final few hundred feet accessible are only accessible through a pit series called The Crevice. It gets its name, the Basement of Swallows, thanks to the birds that fly above its opening. Dave added: 'These caves are spectacular and it's easy to see why so many people visit them every year. My other favorites include Lechuguilla in New Mexico, the caves of Mulu in Borneo, the amazing Xe Bang Fai river caves in Laos, the blue and green caves of France, the amazing lava tubes in Hawaii, and sea caves anywhere but especially the California Channel Islands and New Zealand. By far the best way to get into caving is to hook up with a club or grotto as they are called in the USA. Take a beginner's oriented trip. Also many show caves now offer wild or adventure tours that can give non-cavers a taste of it. In his 40-year cave exploring career Dave has visited Australia, Belize, Canada, China, Cuba, France, Guatemala, Italy, Laos, Malaysia (Borneo), Mexico, Papua New Guinea, New Zealand, Puerto Rico, Slovenia, Spain, Switzerland, and Thailand. Getting ready: The team waits at the top of the cave. Bunnell has explored caves in 18 countries across the world - but this one in Mexico is his favorite Life-long passion: Bunnell, pictured, started diving into caves during his college days and now combines it with his passion for photography, right