Medical Clearance

A group of people gathered inside the hyperbaric chamber.A dive in the chamber creates the same conditions that make divers susceptible to air embolisms, decompression sickness, and nitrogen narcosis in an in-water dive. A current (within one year of the dive) diving physical is required for all participants who wish to dive in the chamber. A copy of a current Standard Diver Medical Exam (RSTC, NAUI, PADI, SSI, etc.), a letter from a physician stating the participant is fit to dive, or a completed Clearance for Hyperbaric Exposure (included in pdf packet) is acceptable. If you are a member of a dive program (scientific, public safety, military, etc.) which has a diving medical requirement, then you may bring a letter from your Diving Supervisor stating you are medically cleared to dive in their program in lieu of the three previously stated options.

Anyone who arrives at the chamber without medical clearance will not be permitted to dive.


All participants must read, complete, and sign a Waiver, Release and Indemnity Agreement (included in pdf packet) prior to diving in the chamber. Extra copies of this form are available at the chamber.

Diving Prior To and After the 165 fsw Dive

A dive in the chamber builds up nitrogen in the body just like a normal dive. The decompression protocol used for the dive assumes that the participants are clear of residual nitrogen. For this reason divers are asked not to dive 24 hours prior to the chamber dive.

Following a 165 fsw dive the participants will have a residual nitrogen load. Because of the depth of the dive we assign a Repetitive Group Designator of “Z” to the Chamber “divers.” Divers are asked not to dive for 24 hours following the chamber dive to 165 fsw, preferably 24 hours. Also, divers are asked not plan to travel to altitude for at least 24 hours following the chamber dives (aircraft, mountain passes, altitude chambers, etc.)


Since the chamber environment has a higher concentration of oxygen molecules than air at sea level we have special requirements for the clothes worn in the chamber. Street shoes are not worn, and all clothing worn in the chamber should be no more than 20% synthetic and preferably 100% cotton (to prevent static electrical sparks). During the descent, the air in the chamber gets quite hot (sometimes over 110oF) and during ascent it can get somewhat cold inside (< 40oF). It is recommended that you dress with the ability to layer clothes (shorts and T-shirt for descent; sweatshirt and sweatpants to add on ascent; and thick cotton socks). Remember all clothes worn in the chamber should be a close to 100% cotton as possible.

Number of Divers

During decompression divers are placed on oxygen at 10 fsw. There are only nine oxygen masks available, so only eight divers (plus our tender) can dive in the chamber at a time. More than one dive will need to be run if your group has more than eight people who are diving.

Time Requirement

Plan to be at the chamber for at least two hours for a single dive. The dive itself will last anywhere from 45 – 70 minutes depending on the bottom time. The rest of the time is taken up by chamber setup, orientation, and collection of paperwork. If more than one dive is required by your group, plan for another hour or so for each additional dive.

Dive Computers & Depth Gauges

Participants are welcome to take their depth gauges or dive computers along on the dive. Make sure that any depth gauges, watches, or computers are rated to depths greater than 165 fsw (50 msw / 6 ATA). Some dive computers should not be exposed to a high pressure air environment. There will be water baths available for those dive computers.


The cost of the dive to 165 fsw is $20 per person (minimum of 4 people or $80). If paying by check, the check should be made out to the USC Catalina Hyperbaric Chamber

Chamber Dive, Catalina Hyperbaric Chamber from Anthea Ibell on Vimeo.

Video by: Anthea Ibell, Australasian Our World Underwater Rolex Scholar, 2011

USC Catalina Hyperbaric Chamber

P.O. Box 5069
1 Big Fisherman Cove
Avalon, CA 90704

Emergency Numbers

Catalina Chamber 24 Hour Emergency Line
(310) 510-1053

LA County Medical Alert Center (MAC)
(866) 940-4401

U.S. Coast Guard Sector LA/Long Beach Search & Rescue
(310) 521-3815
Marine Channel 16

Divers Alert Network (DAN) Emergency Line
(919) 684-9111