Seasickness can be hazardous for scuba divers

Seasickness is a feeling of nausea and, in extreme cases, vertigo experienced after spending time on a craft on water. It is typically brought on by the rocking motion of the craft, but people who are particularly vulnerable to the condition can feel seasick simply by setting foot on a boat, even if the vessel is in dry dock. Image of a seasick scuba diver This photo was taken by Etimbo in the Red Sea in September 2003. ... Image of a seasick scuba diver This photo was taken by Etimbo in the Red Sea in September 2003. ... Nausea (Greek Ναυτεία) is the sensation of unease and discomfort in the stomach with an urge to vomit. ... Vertigo can refer to a number of things: Vertigo is a form of dizziness often associated with balance disorder. ... Water (from the Old English word wæter) is a colorless, tasteless, and odorless substance that is essential to all known forms of life and is known also as the most universal solvent. ... U.S. Navy submarine USS Greeneville in dry dock following collision with a fishing boat. ...

Seasickness can be a debilitating condition and it is extremely dangerous if the sufferer has an important role to carry out, such as steering a yacht through stormy seas while avoiding rocks and other hazards. It is also particularly hazardous for scuba divers who, through dehydration following vomiting, are at increased risk of decompression illness. A yacht was originally defined as a light, fast sailing vessel used to convey important persons. ... Early ideas of autonomous under-water systems appear in Twenty Thousand Leagues Under the Sea Scuba Diving is the use of independent breathing equipment to stay underwater for long periods for recreational diving and professional diving. ... Vomit being eaten by birds Vomiting (or emesis) is the forceful expulsion of the contents of ones stomach through the mouth. ... This article needs cleanup. ...

Cause

Human beings instinctively seek to remain upright by keeping their centre of gravity over their feet. The most important way this is achieved is by visual reference to surrounding objects, such as the horizon. Seasickness often results from the visual confusion on a moving craft, when nearby objects move with the motion of the craft. Because the lines of the masts, windows, and furniture on a ship are constantly shifting with respect to fixed references, humans can suffer a number of afflictions, especially those unaccustomed to being at sea. In physics, the center of gravity (CoG) of an object is the average location of its weight. ... Horizon The horizon is the line that separates earth from sky. ... A mast is a pole which holds a sail of a boat, see mast (sailing). ... Highly decorative Window in a Japanese Onsen in Hakone A window is an opening in an otherwise solid, opaque surface through which light can pass. ... Furniture is the collective term for the movable objects which support the human body (seating furniture and beds), provide storage, and hold objects on horizontal surfaces above the ground. ...

Sea-sickness has such a remarkable effect because both the sense of sight and touch are disturbed by the motion of a craft on water. The severity of seasickness is also influenced by the irregular pressure of the bowels against the diaphragm as they shift with the rising and falling of the ship.

Many experience similar effects while not at sea:

• in railway carriages
• on swings
• while looking from a lofty precipice where known objects, being distant, are viewed under a new aspect and not so readily recognised
• while walking on a wall or roof
• while looking directly up to a roof
• while observing the stars in the zenith
• on walking into a round room, where there are no perpendicular lines of light and shade and the walls and roof are covered with an irregularly-spotted design
• on twirling round, as in waltzing

Tourists in a vis-a-vis, Prague The classic definition of a carriage is a four-wheeled horse-drawn private passenger vehicle with leaf springs or leather strapping for suspension, whether light, smart and fast or large and comfortable. ... The term Swing has several meanings: Swing (dance), a kind of dance, including West Coast Swing and East Coast Swing. ... A wall is a usually solid structure that defines and sometimes protects space. ... A roof is the top covering of a building that prevents the ingress of weather into the building interior. ... This article is about an astronomy term. ...

Prevention and remedy

Over-the-counter and prescription medications are readily available. Some sufferers find that wearing special wristbands also helps stave off the condition. Prescription has various meanings. ... A medication is a licenced drug taken to cure or reduce symptoms of an illness or medical condition. ...

Those suffering from seasickness who are unaccustomed to the motion of a ship often find relief by

• keeping their eyes directed to the fixed shore or horizon, where possible
• lying down on their backs and closing their eyes
• drinking any substance that is likely temporarily to diminish their senses of sight and touch
• move into a position where fresh air is blowing on their face
• sucking on crystalised ginger or sipping ginger tea
• keeping near the centre of the boat where any rocking motion is least pronounced

Unlike with a hangover, succumbing to nausea normally does not relieve the symptoms of seasickness, and, once started, is often difficult to stop. Binomial name Zingiber officinale Roscoe Ginger root is used extensively as a spice in many if not most cuisines of the world. ... A hangover, medically termed veisalgia, is the after-effect following the consumption of large amounts of one drug or another. ...

See also

• Motion sickness