technique. captain horten is tethered to a rope being held on shore by another firefighter. he's swimming out to get me before i head over the next water fall. >> we're trying to get the victim out of there but we can't allow them to kill your rescuer. so we have to go in there with the knowledge, training and experience so everybody goes home at the end of the day. >> and he was saying if you don't have the right geerks firefighters go sometimes, in the water and if the helmet gets under the current, it can actually break someone's neck. it looks rough even after the river is reseeding. how are they successfully able to do this at night? >> reporter: it's still treacherous but you have to fall