Natural Bridge Caverns cavers have had a busy summer.

On three separate expeditions, one spanning a grueling 19 hours, teams of cavers explored never-before-seen rooms, pools and passageways deep in the caverns, which are south of Canyon Lake, just north of San Antonio. The expeditions followed the May 8 discovery of a 600-foot-long passage about 1½ miles past long-established sections of the caverns. When cavers ventured into the new passage, which was first spotted in 1960, they noticed a space beyond its mineral-rich pools of water and mounds of ice-like crystals.

So on June 5, a team of five headed back out to the area to see what they could find, said Brad Wuest, president and CEO of the caverns. The cavers had to climb, crawl, squat and slide in 70-degree temperatures, which can be nice at points but feel chillier when the cavers pause and their sweat dries, Wuest said.

Just beyond the passageway, they hit a fork leading to two areas: one was 100 feet long and the other was about 200 feet long, he said. The 100-foot-long area led into a room, but dead-ended; the other area led into a crawl space.

"I continued on and reached a point where a human could not even fit through it anymore," he said. "That was the end of that direction."

A bit disappointed, the team turned back around to the passage and into a 6-foot-wide crack in the floor. Wuest rappelled down through the crack, thinking he would just go down to area that was already known to the cavers. He tied a rope onto a boulder and inched down, and down, and down.

"I have the realization that I am not descending into the known passage, I'm descending into something further to the north that is virgin passage that no one has ever seen before and it's big," Wuest said.

He hit the bottom after descending for about 90 feet and then walked up to an area of the room that opened up to 4½-feet-deep pools of water and travertine dams formed by water ripples that pushed minerals over the edge of the pool. This area is now called the Travertine Passage.

He saw about 150 feet of more passage, but the team had to leave. He yelled up to the team that he had good news and bad news.

"The good news is we've discovered new virgin passage and it's big and incredible," he told them.

On a second expedition 10 days later, another team went back out to where Wuest had rappelled down to and found a new room, now called Frozen Falls Chamber. The room is the biggest they found all summer and is 135 feet long, 40 feet wide and 30 feet tall, with a volume of 162,000 cubic feet.

A pool, which is about 6 feet deep, and flowstones made of calcite deposits are at the base of the room. When Wuest and his brother, Travis, walked down to a lower part of the room they saw what appeared to be snow.

"Pristine, white, pure as can be, freshly fallen snow it looks like. It's just calcite droplets of water that are falling or flowing into this little lake and they're full of minerals, and the minerals just float to the bottom and settle," Wuest said.

The brothers took their muddy boots off to walk delicately across the area and found another big passage, now called the Flowstone Hall, which includes a formation that looks like a clay pot.

Finally, on the third expedition July 27, more than a dozen cavers went into the caverns to survey all the new spaces and check out the big room they spotted on the previous trip. The room had black formations and white flowstone.

The final expedition took 19 hours, Wuest said. Part of the surveying was done to see if drilling was possible to make future expeditions quicker.

"We're so far back and it's so difficult to get into these sections of the caverns and it's so time-consuming," Wuest said.

Wuest is not sure the public will ever get a chance to get deep into the new chambers, but the discoveries will be shared through photos and videos, and samples are being sent off to the Jackson School of Geosciences at the University of Texas, he said.

Teams will eventually get back down into the caves to see what else is waiting to be discovered.

"We know it's going to be longer than 19 hours next time and so that's daunting, but yeah we'll be ready and we will be going back for sure," Wuest said.

"I tell you, I cannot close my eyes without seeing an image of that virgin passage ahead of me where I stopped and when I turned around last time," he said. "That image is branded in my brain. I see it and it's like, I just can't help but wonder what it's like up there."