Many emergency incidents can lead to extensive flooding which generally leads to abandonment in the worst-case scenario. There are obvious concerns for abandonment with any vessel, but none more so than with the large passenger vessels. Associated problems arise with large numbers of personnel who find themselves in unfamiliar marine environment. SOLAS regulations require passenger vessels able to launch survival craft within 30 minutes of the signal to abandon ship. Individuals who enter the maritime environment deliberately and usually voluntarily expose themselves to a level of risk. For the most part this is a tolerable risk, but if they find themselves in an abandonment situation, exposure to immersion in sea water becomes a much greater possibility. There are known to be four phases associated with immersion, leading to the death of the individual from acute hypothermia. These phases are: initial immersion, short-term immersion up to 15 minutes, long-term immersion of 30 minutes or more, post-immersion, leading to collapse and death.