© Sub-Mission Dive Centre Ltd 2011 © Sub-Mission Dive Centre Ltd 2012 Compartments PADI - Professional Association Of Diving Instructors Sub-Mission Dive Centre Ltd Scuba-Instructors.co.uk Launches New Website For Dive Professionals. Different body tissues absorb and release nitrogen at different speeds These tissues do not correspond directly to a particular body tissue; as such they are classed as theoretical tissues. These theoretical tissues are correctly known as Compartments. Compartments that absorb and eliminate nitrogen quickly are called fast compartments Compartments that absorb and eliminate nitrogen slowly are called slow compartments Haldane identified 5 theoretical tissue compartments The US Navy revised this to 6 compartments The RDP (Recreational Dive Planner) & the eRDPml (Electronic Recreational Dive Planner – Multi Level) use 14 compartments.