Editing Hypothermia (section)

===Water immersion===
[[File:Hypothermia_Training,_Marine_Mountain_Warfare_Center,_California_USA.jpg|thumb|upright|Two American marines participating in an immersion hypothermia exercise]]

Hypothermia continues to be a major limitation to swimming or [[Underwater diving|diving]] in cold water.<ref name="Sterba 1990" /> The reduction in finger dexterity due to pain or numbness decreases general safety and work capacity, which consequently increases the risk of other injuries.<ref name="Sterba 1990" /><ref name="Cheung">{{cite journal | vauthors=Cheung SS, Montie DL, White MD, Behm D | title=Changes in manual dexterity following short-term hand and forearm immersion in 10 degrees C water | journal=Aviation, Space, and Environmental Medicine | volume=74 | issue=9 | pages=990–3 | date=September 2003 | pmid=14503680 | url=http://www.ingentaconnect.com/content/asma/asem/2003/00000074/00000009/art00013 | access-date=2008-06-11 | url-status=live | archive-url=https://web.archive.org/web/20110629184715/http://www.ingentaconnect.com/content/asma/asem/2003/00000074/00000009/art00013 | archive-date=2011-06-29 }}</ref>

Other factors predisposing to immersion hypothermia include [[dehydration]], inadequate rewarming between [[Dive profile#Repetitive diving|repetitive dives]], starting a dive while wearing cold, wet [[dry suit]] undergarments, [[Perspiration|sweating]] with work, inadequate [[thermal insulation]], and poor [[Physical exercise|physical conditioning]].<ref name="Sterba 1990" />

Heat is lost much more quickly in water<ref name="Sterba 1990">{{cite report |author=Sterba, JA |title=Field Management of Accidental Hypothermia during Diving |journal=US Navy Experimental Diving Unit Technical Report |year=1990 |publisher=Navy Experimental Diving Unit Panama City Fla. |url=http://archive.rubicon-foundation.org/4248 |access-date=2008-06-11 |archive-url=https://web.archive.org/web/20110727224238/http://archive.rubicon-foundation.org/4248 |archive-date=2011-07-27}}</ref> than in air. Thus, water temperatures that would be quite reasonable as outdoor air temperatures can lead to hypothermia in survivors, although this is not usually the direct clinical cause of death for those who are not rescued. A water temperature of {{convert|10|C|F}} can lead to death in as little as one hour, and water temperatures near freezing can cause death in as little as 15 minutes.<ref name="Hypothermia safety">{{cite web|url=http://www.usps.org/national/ensign/uspscompass/compassarchive/compassv1n1/hypothermia.htm |access-date=2008-02-19 |title=Hypothermia safety |publisher=[[United States Power Squadrons]] |date=January 23, 2007 |url-status=dead |archive-url=https://web.archive.org/web/20081208180845/http://www.usps.org/national/ensign/uspscompass/compassarchive/compassv1n1/hypothermia.htm |archive-date=December 8, 2008 }}</ref> During the [[sinking of the RMS Titanic|sinking of the ''Titanic'']], most people who entered the {{convert|-2|C|F}} water died in 15&ndash;30 minutes.<ref>[[Sinking of the RMS Titanic#CITEREFButler1998]]</ref>

The actual cause of death in cold water is usually the [[Involuntary action|bodily reactions]] to heat loss and to freezing water, rather than hypothermia (loss of core temperature) itself. For example, plunged into freezing seas, around 20% of victims die within two minutes from [[cold shock response|cold shock]] (uncontrolled [[hyperventilation|rapid breathing]], and gasping, causing water inhalation, massive increase in blood pressure and cardiac strain leading to [[cardiac arrest]], and [[panic]]); another 50% die within 15–30 minutes from cold incapacitation: inability to use or control limbs and hands for swimming or gripping, as the body "protectively" shuts down the peripheral muscles of the limbs to protect its core.<ref name="Vittone">{{cite web|url=http://mariovittone.com/2010/10/the-truth-about-cold-water/|title=The Truth About Cold Water|last=Vittone|first=Mario| name-list-style=vanc |date=October 21, 2010|work=Survival|publisher=Mario Vittone|access-date=January 24, 2017|url-status=live|archive-url=https://web.archive.org/web/20170114154556/http://mariovittone.com/2010/10/the-truth-about-cold-water/|archive-date=January 14, 2017}}</ref> Exhaustion and unconsciousness cause drowning, claiming the rest within a similar time.<ref name="Hypothermia safety"/>