Inclusion Criteria:  18 - 65 years old COVID-19 at least 12 weeks prior, +PCR test and/or documented clinical symptoms Desaturate to <94% during the 6-MWT and/or have abnormal spirometry or DLCO values below the lower limit of normal (LLN) Active life-style before contracting COVID-19  Exclusion Criteria:  Pregnant or lactating women Individuals that are unable walk or get in and out of bed by themselves Weighing over 300 lbs. or Body mass index (BMI) >30 Inability to provide written informed consent Inability or unwillingness to adhere to 10 HBOT treatment sessions over a 2 to 3 week- time period or to complete follow up questionnaires/telephone contacts. Claustrophobia and inability to enter the hyperbaric chamber for session. Inability to effectively equalize the middle ear during ambient pressure changes. History of tympanic membrane perforation, head and neck surgery with compromised Eustachian tube function, including tracheostomy, mastoidectomy, middle ear surgical procedures and cochlear implants. History of pulmonary disease prior to COVID-19 including asthma, chronic obstructive pulmonary disease (COPD), bullous lung disease, previous thoracotomy, pneumothorax or history of pneumothorax prior to having COVID-19. History of cardiovascular disease prior to having COVID-19. History of type 1 or 2 diabetes prior to having COVID-19 History of neurovascular diseases (e.g. recent stroke) prior to having COVID-19 History of uncontrolled hypertension prior to having COVID-19 History of retinitis pigmentosa prior to having COVID-19 History of renal disease prior to having COVID-19 History of seizure disorder prior to having COVID-19 Active or uncontrolled cancer diagnosis. Active or uncontrolled psychiatric disease. Acute upper respiratory tract infection History of exposure to bleomycin Taking the following concomitant medications: PDE5 inhibitors, carbonic anhydrase inhibitors, beta blockers, alpha blockers, nitrates. MRI incompatibilities- a cardiac pacemaker, metal fragments in the eyes, skin, body; heart valve replacement, brain clips, venous umbrella, intercranial bypass, renal, aortic clips, prosthetic devices for middle ear, eye, joint or penile implants, joint replacements; hearing aid, neurostimulator, insulin pump, I.U.D, pregnant or trying to become pregnant, shunts/stents, metal mesh/coil implants; metal plate/pin/screws/wires, any other implants; permanent eyeliner/eyebrows with metal containing dyes, dental work within 6 weeks, claustrophobia. Involved in another clinical trial that does not allow enrollment in other clinical trials.