this is castle rock cave in fennemore, wisconsin. that teeny little hole in the rock where the water is gushing from is where these divers are heading straight into. it is terrifying. i never thought i had a fear of confined spaces until i started watching it. this video is about 11 minutes long and these divers, tamara thompson, and paut lothery, are squeezing themselves into the teeniest little trenches beneath the earth and it's freaking you out, isn't it? >> it is. >> these are the air tanks. this is called no mount diving. they're pushing their air tanks in front of them, through the path that they're trying to go. that right there shows you how small the space is. the fact that they can't even wear their air tanks, they have to push them in first and follow the air tanks through. >> the other crazy part about this is there's a photographer down there shooting all of this. his name is richard dreyer. he is the photographer taking video of these guys. watch this part. this space gets so small he has to take off his helmet to get