Jill sat quietly breathing the gases being fed to her by the large black mask strapped to her face, watching Sharon breathe through the mask's twin securely fastened to her face. They didn't talk much; they would have had to yell to be heard through the masks and the din of the hyperbaric chamber. Slowly the air pressure was raised to a depth of 200 feet, the target of the exercise. The chamber got warmer with the pressure, both girls wearing single piece bathing suits to keep cool for now. Smiling occasionally to each other was all they could do for now. "You can take your masks off now", a voice over the speakers announced. Jill and Sharon took off their masks and rubbed their faces where the masks had been, leaving an impression where the rubber had been on their faces for 2 hours. Jill quacked, "I'm okay,HAHAHAHAHAHAHA!" as she heard herself for the first time on heliox. Sharon too was rolling in laughter and confirmed her well being. After the giggles had subsided the girls took stock of their task- another step towards using underwater liquid breathing systems. Since both Jill and Sharon had extensive experience with unusual breathing apparatus they were loaned out to the underwater branch of the respiratory research institute. That suited them both fine, this being another chance to be intubated and ventilated for the advacement of libido, er ,science. Sharon powdered her legs and arms, Jill powdered Sharon's back, then they switched. Jill pulled on her wetsuit bottoms, slowly cinching them up her legs. Sharon helped by pulling the back up over her friend's bottom, making friendly contact in the process. Jill smiled and turned, making sure they couldn't be seen and gave Jill a quick kiss. Pulling on her wetsuit top, Jill saw Sharon climb into her back-zipped one piece wetsuit. The smooth front piece of Sharon's suit clung to her breasts very attractively, as Jill zipped the rear seam shut. "Are you ready to go to the pool?" Sharon asked. "I am", Jill said, "are you ready for us to move on?" she asked to the observers outside the chamber. "Take your time, don't rush it, but proceed." Sharon was eager to be intubated, Jill was eager to do it for her. Sharon sat on the edge of a fold-down cot as Jill brought over the intubation tray and sat opposite her. Jill inflated the tube's cuff with a non-expanding fluid, checked it's patency then deflated it. Jill then pulled on her exam gloves and Sharon pulled back her hair and banded it behind her head. Panting a little, Sharon bent forward to make it easier to be intubated. Jill lubricated the tube and put a wire in the tube to hold it in a J-shape. Jill didn't have to ask, Sharon opened her mouth and waved in the motion one would use to put a tube down a windpipe. Jill put the tip of the tube in Sharon's mouth, easing it over her tongue. Passing the back of her mouth, Sharon adjusted her head's position to help Jill find her airway. Both girls helped each other get the tube in Sharon's larynx; Sharon gave a slight cough and motioned for the guide wire to come out. The tube moved closer to her vocal cords, Sharon coughing in a controlled fashion. The coughing stopped as the tube went gently past her cords, replaced by rapid exhales through the tube. As Jill pushed the tube to Sharon's preferred depth Sharon calmed down, her body knowing that coughing would not help her anymore. Jill inflated the cuff with fluid and held the tube in place with her hand, "are you all right?", Sharon giving an OK sign. Jill taped the tube in place with a hypoallergenic and waterproof tape, using liberal quantities to ensure no accidental extubations. The tube was shorter than a standard endotracheal tube and the next piece of equipment was why; Jill hefted a full-face diving mask onto the cot next to Sharon. The mask had special ports for fluid breathing built into it, where a diver could switch over without changing masks. The endotracheal tube was needed so the diver wouldn't breathe saliva (or vomitus if it came to that) or swallow a lot of breathing fluid. Sharon looked over at the mask apprehensively, even though she had been fully trained in a pool with it for several days. Jill said, "when you're ready..." Sharon nodded and lifted the mask to the face. Jill reached under the mask and guided Sharon's tube into the breathing circuit's socket. Sharon was breathing air from a hooka system now, the long air hose leading to the chamber's small pool. Satisfied with the tube's connection, Jill helped Sharon don the mask the rest of the way onto her head and face, then adjusted the straps. Sharon sat there holding some of the mask's weight in her hands as she became accustomed to the feel, and Jill rechecked the connections; Sharon's life was dependent on Jill's skills now. Sharon moved her head around, making sure all was well, then stood before going to the pool. Jill followed her closely. Sharon sat with her legs in the pool, then Jill connected the liquid breathing circuit to Sharon's mask and strapped the apparatus to her back. "Like I told you about when I was breathing liquid, this has a powered ventilation circuit. You will breathe slower and deeper, and the machine will help" Jill said and Sharon acknowledged. Jill then grabbed a full face mask off the wall hanger and joined Sharon poolside. Jill donned her mask and adjusted the straps, breathing exaggeratedly to test the circuit. Sharon was feeling nervous, knowing that if anything went way wrong, she couldn't just walk out of the chamber without severe "bends". Sharon turned to see Jill looking deep into her eyes through her mask's faceplate, her mouth and nose covered by the nose cup. They held hands and rolled over into the water. Floating to the bottom of the small pool and finding a space between the equipment, Sharon and Jill still held hands and looked to each other in support. Jill let go and signaled "OK?", Sharon thought for a second and replied OK. Jill swirled her hand for Sharon to switch on the liquid ventilator. Sharon slowly did, and felt the vent take over her breathing. Feeling relieved, she was startled by the arrival of the fluid into her tube and lungs! Sharon reached for her mask, "GET IT OFF GET IT OFF!" she thought rather loudly!! Jill was way ahead of her and quickly grabbed Sharon's hands before she did anything bad to herself. Sharon became rigid in fear as the vent kept pushing the fluid into her and life-giving air was bubbling out of her lungs through the tube swollen in her windpipe! Sharon was shaken by Jill, and slowly opened her eyes. She was alive but horribly uncomfortable with the fluid in her lungs. She sat on a stationary bike in the bottom of the pool and collected herself. Jill loosened her grip, Sharon now calmer and not likely to hurt herself in a panic now. Sharon sat for 20 minutes getting used to the ventilator's rhythm but never comfortable with it. But she was alive and conscious and letting the machine do her breathing. Jill was bubbling alongside her, hugging her reassuringly. Sharon finally signaled that she could carry on a few tests on the bike. Jill helped her feet into the pedal stirrups, and Sharon began pedaling. Sharon began feeling faint after a few minutes, and stopped to adjust her ventilator. A few breaths later she began again, taking better note of her respiratory needs and adjusting the vent to meet them. Jill wrote on a slate, recording her friend's reactions for study later. Soon Sharon stopped, waving that she couldn't go on. Jill swam to her side with the slate, letting Sharon write- "too much for now, need rest. hard to get used to but feel like could get better with practice". Jill nodded with an OK thrown in, understanding full well that liquid breathing like this is stressful. The girls stayed underwater for a while, Sharon taking different attitudes in the pool to evaluate breathing in different positions. Her favorite position was hugging Jill, which they practiced often, their wetsuit-clad bodies held against each other tightly. Sharon and Jill swapped crotch grabs, then Jill unzipped her wetsuit top and pulled down her swimsuit to expose her breasts. Sharon rubbed her facemask against Jill's nipples, wishing that contraption wasn't in her way! Jill massaged Sharon's breasts through her smooth wetsuit, Sharon feeling it in a muffled way. Jill and Sharon surfaced after 2 hours underwater. Jill took off her mask and reported to the observers quickly then went to help Sharon out of her gear. Sharon had gotten used to the breathing gear, if not completely comfortable with the liquid in her lungs. Jill said, "let's get you to the cot and get this off you", Sharon agreeing. Sharon sat in the place she had been intubated hours ago. Sharon held the mask onto her face as Jill loosed the straps then reached under the mask's seal to hold her endotracheal tube. Sharon the slowly lowered her mask as Jill made sure her tube didn't get pulled out accidentally. The tube disconnected as Sharon was halfway though an inhale; this time the air startled her into a cough and liquid flew from her tube onto Jill's chest! "That's okay! I felt the same way!" Jill chuckled in a chipmunk voice. Sharon broke a smile and laughed silently and gurgled as she ejected more fluid from her lungs. Jill talked to the observers for a few more minutes as Sharon became used to breathing air again, then Jill drew the curtains closed over the chamber's viewing ports and turned off the A/V monitors. Jill stripped her wetsuit top off with Sharon's help, then unzipped Sharon's. Soon both were sitting naked and toweling off. Jill attached an ambu bag to Sharon's tube and started giving her large amounts of air to help rid her lungs of fluid. Seeing her sitting there nude, taking big hits of air from her bag through her ETT, Jill was visibly turned on, Sharon returning the notion by brushing Jill's breasts with her fingers. Sharon wilted onto the cot, Jill following with her bagging. Jill found herself giving the bag to Sharon, needing both hands to fondle her breasts and moving to Sharon's crotch began her ritual of incessant licking. Silently, Sharon moved her mouth as if to moan, her tongue feeling around the tube leading to her windpipe. Squeezing air into herself, then teasing her own breasts, squeezing another breath, pulling gently on her nipples, she let the excitement carry her to a rapid orgasm! Jill rubbed herself, tasting the tangy salty fluid of her friend's vagina, debating whether to intubate herself or not when Sharon held a endotracheal tube to her face. Reaching for it, Sharon pulled it away and pointed to the other cot. Jill shivered in delight; Sharon wanted to intubate her! Sharon sat the bag aside for now and got gloved up. She checked her equipment, and motioned for Jill to lean toward her. Carefully Sharon lifted the lubricated tube to Jill's shaking lips. Jill moaned out loud as the tube passed her tongue, into her larynx, the moaning resonating through the tube. Gently passing her vocal cords Jill's moans were replaced by the stuttering, quiet hiss of her uninhibited breathing. Jill was shaking in adrenaline rush as Sharon inflated her cuff, blocking her airway to all but the tube. Jill felt another rush as the cuff swelled in her throat, so full and thrilling!! Sharon taped her tube in place, then gave her friend and lover several sharp breaths with the ambu bag. Jill leaned back, her butt just on the edge of the cot, legs spread and fingers reaching deep into her folds. Sharon rubbed Jill's breasts then lowered her mouth to them. Reaching around her tube she licked and sucked as best she could; Sharon loved to suck Jill's tits! Jill let the bag dangle from her tube, looking down to see Sharon; Sharon's face sideways to her nipples, tongue licking from the corner of her mouth, Sharon's tube pressing against her breasts as well. Jill shook her crotch-buried hand hard at the sight of her intubated lover and herself, both breathing in hisses thought their tubes loving placed by each other!! She surrendered to herself, cumming for what seemed hours! Slowly recovering, Jill saw Sharon bagging her, then felt the rush of air as they hugged with the bag between them. She listened to Sharon's breathing tube beside her ear, a very reassuring sound; as her breathing through the bag's valve was to Sharon. Unfortunately, Jill had to be extubated to communicate to the observers who would obviously be wondering why it took half an hour to change into dry clothes! Sharon carefully peeled the tape away from Jill's tube while Jill held her tube still. Feeling Sharons' breath from her tube, Jill fought hard not to go at it again! Jill clenched her tube gently and stroked Sharon's face, Sharon nodding knowingly but Jill needed to be able to talk. Sharon deflated Jill's cuff; Jill breathed a deep breath and pulled her tube out in one smooth well-practiced motion. Coughing, Jill reluctantly tossed the tube into the trash. Both girls then pulled out their dry clothes. After checking with the observers, Jill switched the A/V off again so they could get some sleep. Sharon was going to remain intubated for the night, and Jill set up a ventilator to assist her breathing in case of complications. She suctioned Sharon, then tucked her into bed. Jill connected her to the ventilator, set the alarms and kissed her goodnight. Jill watched as Sharon quickly went to sleep, exhausted from the day's activities. "Sleep well, Sharon. I'll be here for you always!"